No, iChat itself isn't starting, just connecting to the Net.
I have DISabled "when I quit iChat, set status to Offline" because, like I said - I like to stay "away" just so I can see who's online but they can't necessarily see that I suddenly came online when I reconnect to the net.
Taking it out of the menubar might work; I'll try that.
If not, I guess there's no way to do it. I guess it figures if it's in the menubar and you re-connect you are automatically "available".