From the article: PayPal allegedly sent his wife a letter that says she "violated PayPal's User Agreement and Acceptable Use Policy (AUP) by accepting payments for the sale of injectable fillers not approved by the FDA."
If PayPal DOESN'T freeze the account and hold the money, they can get in far larger trouble with the government. Why should PayPal be involved in this enforcement at all? If the FDA doesn't like what this seller is doing, let the FDA themselves go after the seller and leave PayPal out of it. But the law doesn't work that way.
I had $10k's in an account with BofA that was frozen and nearly killed the closing on a house I was buying at the time. Because they had a mailbox address on file for me, rather than my home address. It was horrible for me, but that's what the says that they had to do, and if they didn't the could end up in trouble with the feds facing huge penalties.
Let's try to empathize with all parties and think rationally about the incentives and constraints that they face.