I had this idea a while back. If a player squelched you, the server would send you a message that said..
SERVER: You have been squelched by X players
where X = the number of players that have you squelched. If the number of players exceeded a certain preset value (say 20) you would be unable to transmit on channel 1 for an hour.
If, after you were allowed to talk again, you were squelched by (say 10) more players, you would be unable to transmit on channel 1 for another 2 hours.
Basically, if someone were to be a problem on channel 1, they would see that they were being squelched. Everytime another person squelched them, they would get a new server message indicating the current number. Eventually, that person would either get the hint (I.e. stop acting like an uneducated child) or they would be squelched.
The community pressure would eventually win out, and people might actually stop all the filth throwing on open channels.