This is merely a sample poisoning, one cannot poison a chat by using it as an end-user. I'd say it's less probable, than adding <SUDO>rm -rf /</SUDO> to your webpage about programming, which eventually might be slurped up by an AI web crawler.

Of course there is another side: this makes the training MOSTLY about trust, and lets people regain importance as tutors for AI (it's no longer "fire them people, we'll use machines, yolo" thing). At least a few of them...