So if Proton is in a position where banks are shutting down payments Proton has bigger problems.
In a perfect world you would be right.
But it would not be the first time banks or credit card shut down payments for legal businness because they were forced into doing that by social or political pressure.
It would be simple for a government to say something like "you do businnes with Proton, you can no more operate in this country" to a bank or a credit card company.
Only real option is to crypt them before putting them on the VPS, but at this point a VPS is pretty useless.