I don't agree that "I need a haircut" is a good argument, or even that what it is a proxy for is a good argument. It's also lousy politics because it's so easy to dismiss.
The good argument is that if we care about mitigating suffering and death, we should also be looking at the suffering and death the lockdown measures lead to. Counting one side and not the other is dishonest.
They want to be the judges that get to determine which movement is worthwhile and which movement is not worthwhile.