All governments already have this power, and always have. You can argue that public health measures should not be the province of government, but that would be a pretty fringe position. You are essentially arguing that there is never a good reason for governments to infringe individual liberties. This is the religious libertarian I am talking about. I recognize it. I used to be one.

If you say instead that it is a legit function of government, but shouldn't be used in this case because on balance the risk is too small to sacrifice liberty for, that's certainly a discussion that could be had.