This seems a little paranoid, yes. :) What text do you envision copying from Twitter that's going to specifically include their special logo character? It's not going to be in anybody's tweet text.

> Because they're using the "Private Use Area" of the font improperly...

Uh, isn't putting your own characters in Unicode's private use area specifically what that area is for? Isn't that where fonts that have dingbats unique to them, for instance, would put them?