Well, I mean ... it's effectively a lockout, but if they're successful in proving Force Majeure* then it wouldn't technically be a lockout. Force Majeure basically releases both sides of responsibility for circumstances beyond either's control. It's been used in pandemics before, so there would be legal precedent in the US for sure. The players can and would fight it, but I don't think they'd win. If there's no way for the NHL to operate under the current conditions without guaranteeing a financial loss, and you can invoke the "act of God" clause with a straight face ... yeah. That's what the thing is there for.
Now, doing that would re-set the labor relations clock to "we're actively at labor war over every single thing, no matter how small" ... but I don't see a way out of this where they owners don't have to basically fund around 50-70% of operations out of their own pockets (depending on TV/radio revenues) and that's not sustainable or even reasonable.
* cant remember if the correct terms is proving or perfecting, but (like bankruptcy) you can't just shout "force majeure" in front of the courthouse and call it a day. You'll have to convince a Federal Judge in the NHL's assigned US District that you are justified in asserting the clause in the CBA. Again, given the precedence of FJ being used during pandemics in the past, it's as likely as not to be successful should the owners want to drop a bomb on their relationship with the players in this manner.