I would be happy to move a certain comment discussion with a new member to chat as suggested by the auto message—but that question asker has one 1 rep. She wouldn't even be able to comment except that it is her own question.
- Don't show the "move to chat" suggestion one of the participants has insufficient reputation.
- Drop the rep requirement for chat rooms, but give highly privileged users (say 10K or higher) in small sites the ability to "kick out" spammers or offenders who have not earned reputation. Not sure what the business rules would be here, but it is probably worth a discussion in the design team.
- Preferably: create a special chat room, and given that new user permissions only for that chat. In other words, a new user can enter a chat room only when created for them by a reputable user, and they are therefore directly invited.
It doesn't help to tell me that I shouldn't engage in a long discussion, when there is no other way to communicate with the new user :-)