I wonder if mods will be less likely to move / delete PMP threads because people could complain and demand refunds or something.
Nope. They'll remove offending threads whether they're PMP'd or not. I've seen the "I put a lot of Cash into this site!!" arguments before, especially when it comes to permabans. Doesn't matter how much money you put into the site. Buying Cash items doesn't mean you're exempt from the rules.
If a thread is moved from someplace it doesn't belong, well, then it's put where it DOES belong. And if the user thinks the mod or FA is wrong, they can always get another mod to take a look at it for a second opinion anyway.