IMO this is a bad call and makes Pinside feedback no longer a source of establishing trustworthiness.

I am sympathetic to that point too, it puts Robin in the role of judge/jury.

IMO the best solution is to allow pos/neg feedback and be 100% hands off about it.
Fake feedback will become apparent through posting patterns over time.

Is there such a thing as a solicited negative recommendation?

"Hey, I just ripped you off, can you make sure and post about it on Pinside? Thanks sucker!"

EDIT: I learned reading comprehension and see that we can still leave negative feedback when it's associated with a pinside transaction. That makes a little more sense to me, though I still feel we need a way as a community to warn each other of bad traders. I'm not sure what the best mechanism for that is though.