Just to make the math easy, let’s suppose the gouging tax is 50%.
The air purifiers problem seems like not a big problem? If they are normally “worth” $150 and you value having them at $300, you could post them up for sale at $450. Then, if someone really needs them, you get your $300, they get their air purifier, and $150 goes to disaster relief. This tax only prevents the trade if the buyers would buy them for $300 but not for $450, which limits the amount of deadweight loss here to a maximum of $149, rather than potentially unbounded deadweight loss under current policy.
This idea kind of rhymes with gain-of-function research in a way that makes me uncomfortable. “Let’s intentionally create harmful things, but its OK because we are creating harmful things for the purpose of preventing the harm that would be caused by those things.”
I’m not sure if I can formalize this into a logically-tight case against doing it, but it seems conceptually similar to X, and X is bad.