The Covid crisis and the politics of independence ploughed into one another this week, and it wasn’t pretty.

They were set on a collision course when Edinburgh University public health expert Professor Devi Sridhar suggested that quarantine, screening or testing for visitors from England should be considered if the virus was continuing to circulate at higher levels there as Scotland’s incidence continued to fall.

Nicola Sturgeon confirmed she was not considering any such move at present but hadn’t ruled it out.

Boom. Outrage erupted. Scottish Tory MP Andrew Bowie accused the First Minister of “deeply irresponsible, damaging and divisive” talk. “Absolutely astonishing and shameful”, barked the Prime Minister, before declaring to general bafflement that there was “no such thing as a border” anyway.

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So then Nicola lobbed one back at him, over whatever that line on the map is between Scotland and England. She accused him of “disgraceful” behaviour for trying to turn the issue into a constitutional row (we know how much she hates those) and dismissed his border comments as being “absurd and ridiculous”.

Quite possibly if you were following all this, your heart sank. With whiplash speed, after several months’ respite, we were having a ding-dong over Scotland’s relationship with the UK, this time in the context of Covid itself. It’s never edifying to see people fall off the wagon.

I’m afraid that if there is scepticism about Ms Sturgeon’s motives, then she is merely reaping what she’s sown. You can’t spend years and years inflating every disagreement with Westminster into an “outrage” or an “insult” without fostering some cynicism about your motivation. How would she have reacted if Mr Johnson’s government were the one speculating about a quarantine of Scottish visitors? It’s not hard to imagine.

But was Nicola Sturgeon guilty of deliberately stirring the pot for political reasons in the middle of a crisis? I don’t believe she was. Whatever one’s view of the First Minister’s peacetime politics, she has been locked on to the Covid crisis for months now with the focus of an ultramarathon runner. Her awareness of her personal responsibility for its outcome has been palpable.

There is a scientific rationale for considering such a quarantine. Scotland’s goal of “eliminating” the virus (reducing cases to negligible levels and ending community transmission) would create the conditions for near-normal life to resume and in particular for schools to re-open full time.

The goal of the strategy in England, by contrast, is a bit hazy as you might expect from this Prime Minister but appears to be keeping levels low enough so as not to overwhelm the NHS while opening up the economy quickly. This could result in a different infection pattern there. A local lockdown has already been imposed in Leicester due to a spike in cases and the infection rate is relatively high in some other places too.

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Meanwhile, there are precedents for domestic quarantine elsewhere: New York and certain German states have imposed them on those coming from higher incidence areas.

In the event that Scotland had suppressed Covid successfully for a period of time while England had not, the public expectation would be for the First Minister to protect Scotland’s position (though many tourism and hospitality businesses would understandably object).

Even if you incline to the mistrustful view that Ms Sturgeon is so obsessed with independence that she wouldn’t think twice about using coronavirus to bait Westminster, it makes no sense as a political strategy. Who would she be trying to impress? Her own supporters? Even with the SNP heading for the rapids over the Salmond inquiry, she has far more to lose than gain from being seen to indulge in petty constitutional point-scoring. The First Minister has maintained approval ratings since March to make other leaders seethe with envy, having exercised restraint in relation to the UK Government. Amazingly voters seem to like it when politicians devote themselves to issues of immediate importance instead of trying to knock spots off each other. Both the SNP and the independence movement have benefited from Ms Sturgeon’s rising reputation, as the polls show. Why risk it all unnecessarily?

It’s true that this quarantine talk underlines Scotland’s relative success in suppressing the virus latterly, which could have political benefits for the First Minister, helping cement trust with the soft no voters who will decide any future independence referendum and giving her government some ballast for when the public inquiries take place on its handling on the crisis. (That process will shine an unforgiving light on some of Ms Sturgeon’s decisions, such as the timing of lockdown, protecting care home residents and testing. Come the next election, having handled Covid better than Westminster will matter.)

But these are fringe benefits, not political strategy. It would be a reckless leader who tried to exploit the Covid crisis when so much could still go wrong. The downward trajectory of infections in Scotland could easily be reversed; how hubristic talk of a cross-border quarantine would sound then. We’re already seeing a cluster of new infections in Dumfries and Galloway, with five-mile travel restrictions being maintained there. As lockdown eases, more such outbreaks are highly likely. We have a plan; whether the virus will co-operate is another matter.

READ MORE: Dumfries and Galloway residents caught in cross-border Covid outbreak told 'don't travel to pubs in England'

And imposing a cross-border quarantine wouldn’t be straightforward. Some Scots would oppose it. Tourism is economically more important to Scotland than to the rest of Britain; many island businesses, for instance, depend on it. In those communities, there is fear of holidaymakers causing localised outbreaks and putting health services under pressure, but at the same time businesses could go under without an influx of visitors.

That’s before you get to the question of how to enforce quarantine arrangements.

The Scottish Government is also caught in a dilemma over air bridges, which would allow visitors from up to 75 countries to enter the UK without quarantining on arrival. Ms Sturgeon is under pressure from UK ministers to approve the plan, but if she green-lights it, it could make it harder to argue for future quarantines.

Even so, it makes no sense to rule anything out. There is at least a chance Scotland will hold the course and be Covid-free by the end of summer.

If so, then the Scottish Government must surely be prepared to consider all means of keeping it that way.

All columnists are free to express their opinions. They don’t necessarily represent the view of The Herald.