If they can pick out that kind of behavior they can filter it for training. This is probably more to protect them legally so when they shut down a user they have something to point to.
That people are getting angry and insulting to an LLM shows they don't understand the technology (true of most of technology really), and probably think it's actually understanding them or even caring. Really embarrassing and sad when you picture an LLM output like a type of a mirror, GIGO. And the mental health aspect of users is a huge issue that's not being talked about enough, and also being exploited to sell a solution.