I think it's much simpler than that, it's based on some emotions we've faced since the beginning of time: fear, vengeance, and equity.
I'll start with vengeance, since it's a bit easier to describe. We have a person who comes here with concrete proof that -something- was taken out of his bag by the accused. The accused refuses to answer for it and instead only antagonizes. All of us standing by hate this (and he knows it) because it feels like the good guy lost. The bad guy isn't supposed to get away with it and then wave his victory in our faces. Bad guys get punished.
In terms of equity, we're talking about equality of punishment. Con and whoever else gaming the PP requirements were banned for doing so. Considering how the general opinion of having a minimum PP is already on the fence with the community, and that it was at a pre-release, the public did not see it as a big enough deal to warrant a ban. They gamed the system to gain access to an event, which is an offense that didn't really bother many people. After all, it doesn't really hurt us (us being the playing public). Then there was the hotel poop incident, which happened AFTER an event as well, and while it caused no harm to anyone, they were banned for hurting the image of the game. Now we have someone stealing - with proof- and when presented with the proof, TCPI doesn't do anything NEARLY as detrimental to the parties involved. That doesn't seem fair. In our legal system, for example, you'll rarely if ever get as much time in jail for theft as you would for murder, because the severity of both is different. The players in this situation feel that the severity of theft is greater than that of poop in a hotel room or cheating at a pre-release, and it feels like the punishments are inverted.
This brings me to fear. There's a reason that in our legal system there are different sentences and gravity assigned to manslaughter, first degree murder, second degree, etc., and some of it IS indeed based on fear. The thought of some crazy person planning our your death for years and then carrying it out in cold blood is scarier to us than someone getting into an argument with us and murdering us over that. The same could be said here. We are much more afraid of a $1000 item being taken from us than we are of someone cheating at a pre-release, or leaving poop at our front doors. We feel that the punishment for something that adversely affects us in a bigger way and causes us to feel terrible emotions regarding loss, fear, & panic should have a higher punishment than those other situations that may make us go 'meh'.
So in conclusion, I feel that most people's prime fear here is that we are allocating punishments unfairly and that we fear the lack of punishment might mean this can happen again in the future. As to why we don't feel this way about EVERY theft, I seriously think it comes down to the amount of transparency on the issue. Here it's very clear - Mees posted pictures and the letter, and we saw TCPI's response to what he sent. It's not a mere 'he said, she said' thing - it's solidified now. If Mees had no proof, we wouldn't be so upset because we would 'understand' their decision - ie, they don't have enough proof so they can't ban a player over it. Over here they do.