First off, the ban is for 15 minutes only, so I think it's meant more as a slap on the wrist than anything else. It'll probably expire before I've even posted this reply.
Not really much point threatening to ban, this usually only causes more complaining from the server. If one player or an entire team of players is breaking some rule warranting a ban (especially members), just do it.
I don't know if chick plays with !enemyvoice turned on or off, but in general you shouldn't assume that just because something was said into the mic that this means an admin heard it.
Rushing is always a tricky subject to deal with... Anyways, I see two players banned for 15 minutes apiece.