I wouldn't necessarily support this just for the fact that usually the greatest percentage of people that need help in the chatbox are users that don't ever necessarily use the forums unless they need assistance. If they couldn't join the chat-box then they'd resort to making threads which I'd rather avoid by letting everyone use the chatbox freely with no limitations. However this is just my opinion, if the majority of OSBot would like to see this implemented then I wouldn't be opposed.
Whatever makes the community happy, thank you for the suggestion!