He's probably just banned from whatever server the java client is using. It's probably just a temp ban though, for too many concurrent connections or something, it's been happening a lot lately. Simply using a different server (via a real IRC client) will most likely fix his issues. If that doesn't work, then I'd go the proxy route, but that would be a last resort as they tend to be pretty slow. Also, the proxy would have to support IRC for it to even be worth the effort.