I think the micah trade can be ignored, although it clearly did inform the decision to give fairportmagic negative feedback in this case. I think the real sufficient cause for punishing fairportmagic was because after he was told that it was against the rules to post a BTR as quickly as he did his response was something like "yeah but I did it anyways because I still think this guy is sketchy." That indicates a willful disregard for the rules and I think that punishment is fair.
Back to the main point. So fairpoint see’s Micah doesn’t pay anything. He gets a couple bucks and a scuffed/scratched JMTS when he really wanted a minty one. He isn’t happy. So he vents on the internet. Should he have kept his words to himself and not posted again? Probably. Was his anger understandable? To me it was. He sees the situation as someone just got away with a bad trade and will suffer no consequences. You got upset in return because you tried to resolve this to the best of your ability by still taking the loss, and to your POV he is ungrateful. So your annoyed with this guy, then a couple days later he posts a BTR because he is nervous and impatient with a new user about a trade. You think “what is it with this guy he’s a pain in the ass he needs a lesson to knock it off” or something like that. Fairpoint is thinking “god I’m going to get ripped off again why do I keep having problems with traders on this site!” so he posts a BTR early.
You're missing a crucial element (edit: okay, you bring this up later in the discussion), which sebi has brought up and which I noted in the thread was alarming - that after sebi had rendered his decision, fairportmagic openly talked about trying to get a Paypal refund anyways. Trying to skirt the consequences of an admin decision like that should definitely be against the rules, and people should know better than to think it's okay. fairportmagic may be rightly annoyed with his trade partner, but a neutral third party couldn't determine micah's guilt and part of using the BTR system is that you have to be willing to submit to the decisions of that third party, whether you feel annoyed by it or not.
Furthermore, fairportmagic's attitude was pretty antagonistic throughout, implying that the decision should go his way because he had more karma, basically accusing micah of marking his cards (he backed off of this), not accepting a refund, etc.
And I think it's fair to make note of a user's shitty/antagonistic attitude in one dispute and use that as part of how you render a decision in another. It doesn't mean you're punishing him for the first instance of bad behavior, but that you're just using what you've learned about the user to better-understand what's going on in the next dispute.
I don't think all of these issues need to be mixed together. How the fairportmagic/micah trade should have been resolved (an interesting issue in its own right) can be discussed separately from how his dispute with M Lee should have been handled.