I don't think kicking someone off an internet chat channel is actively reducing the possibility of Iran use of Bitcoin.
Based on his comments before the ban he is very much against talking about it at all. There are many other public venues of talking about it and I think this thread and the coverage it currently has in Reddit is actually much more public than a darn IRC channel. What he did gave it 100 times more publicity than it would've got if there was just a discussion in an IRC channel.
I also wanted to comment on the Silk Road comment that you removed and I'll just say that I think the policies regarding talk about Silk Road are ridiculous as well. Silk Road is an anonymous marketplace by definition. Talking about it, using it, does NOT imply illegal activities. Silk Road itself is NOT illegal. I have actually consulted this with a lawyer because we've run into users in our service that talk to us about Silk Road. As long as the user doesn't mention drugs or other illegal substances, we have no problem providing service to people who mention Silk Road.