As a lawyer, I would advise my clients not to attempt a chargeback. It's possibly illegal (a minor form of business fraud), although I would admit that nobody's likely to do anything about it.

As a frequent flyer, I would advise anyone who values their status with an airline or their RDM's not to attempt one, because I could totally envision there being consequences in that regard.

If a person is not a FF'er with UA and wants to take a calculated risk, I don't object to you presenting it as an option. But the sort of broader arguments you are making about it are wrong. It's more accurate to say "the procedure is available, but there's a significant likelihood you are going to get denied given the current circumstances, and discussions of chargebacks pre-coronavirus probably have little applicability here. But if you want to try knowing the risks, you can."