Why is this person still allowed to post here?

This is something that comes up semi-regularly...most recently in a BOI thread. (Let's leave the names out of this because it's a generic issue - it really doesn't have anything to do with specific individuals.

Mr. Moore, I am a little confused as to why this individual is still allowed to post here. I live in south Florida as well and have seen multiple rediculous craigslist ads posted by him. If I am in the wrong by saying this my apologies. Please explain

Simply his demeanor towards animals, I've seen his ads everywhere. We all have. But for the unsuspecting newbie that may read his ad without reading the boi. I feel sorry if they send him turtles. I may be wrong here but I feel (out of morals) he shouldn't be allowed here. I don't post much but I do enjoy reading the site daily.

There are a lot of people I don't particularly like seeing here - it doesn't really matter if they are annoying, givers of bad advice/information, thieves, liars, hoarders, trolls, or just plain dumbs. The scammers and thieves are probably the most difficult to tolerate...but, as has been said for as long as I've been on this site, the moderation team does not serve as judge, jury, and/or executioner in those matters.
Regardless of the category into which somebody might fall, we don't simply remove people based on (lack of) popularity, "moral" judgement, etc. Basically, the criteria for getting banned comes down to violations of site rules/policies. People whose posts violate the posting rules get infractions, which lead to bans if the behavior doesn't change (there, eventually, go the trolls). The other big reason that people get banned is providing false information at registration - particularly the name field, but the DOB and location can sometimes come into play as well.
Part of the reason that this site can do what it does is that people are not allowed to post anonymously, or under false names. On the BOI, the full name requirement gives each person ownership of their words. That requirement was extended to the classifieds (along with requiring City and State in the location field) to offer a modicum of protection for buyers and sellers. If the names or locations provided during communication don't match the profile - common sense should tell people to beware....we also ask that those situations be reported to us, so we can investigate.
<Sorry - got off on a bit of a tangent>
Back to the subject of removing people for moral (or other) reasons. Removing people due to accumulated infractions is simple and straightforward - easily justified. Same for providing false information during registration. Anything else quickly becomes a grey area. How do we quantify moral decisions, so that they can be applied as consistently as possible by 7 different people with different backgrounds, attitudes, and perceptions? Further, if we were to ban people based on such criteria, it could be construed as akin to saying that anybody who has not been banned passes the muster, so to speak.
It comes down to the simple fact that we cannot create/maintain environment that is safe from scammers, mistreaters, and dumbs...at least not without costly measures that would likely kill the site (and still not be totally effective).