I don’t agree with either claim: I don’t think they’re security theater, and I do think they universalize, contingent on there being security parties that are incentivized to scan packages.
The latter is a big assumption, but I think it’s a win for us either way: if supply chain companies are actually capable of defending us, then we win. But if it turns out they can’t serve as the cooldown vanguard, then we have great evidence that they shouldn’t be trusted at all.