Your concerns have been anticipated. Here's how the situation is going to play out:
First, you send your model only to me. I swear not to distribute it, use it, maltreat it or feed it after midnight. For those of a legalistic persuasion, I will be happy to sign a reasonable contract to that effect (reasonable meaning that it doesn't include little clauses about my soul or first-born children: you can have my cat though, if you want). Basically, I want to give you every reason to trust me on this, because it's about the only way things are going to work.
Second, the other members of the club do not get your model. They get a public version which will have only the important skeletal structures, and a simple mesh showing only the major body shapes of your character. This is so (a) they can see the motions of other characters in a choreography in A:M, and (b) they can animate the character themselves, if and when you give them permission to do so (see Character vs. Character combat).
So, altogether, the only risk you take on sending out your model to the Brawl is... well, me. And I know myself to by trustworthy. How can you know this? Well, you can take my word on it.
OK, enough about privacy. Stupid topic anyhow.