i think you're attributing far too much cunning and big-picture thinking to developers. specifically, the logic chain here would have to run "this dude is telecommuting, which means that he can live somewhere cheaper than sf, which means that he can accept a lower salary, which means that salaries across the board will tend to drop, which means that my salary will be affected, which means i'd better shaft him". i'm not saying that a malicious developer can't whisper into the right ears and get someone into trouble, but it's usually because of some more directly personal dislike or jealousy.