I find it hard to believe that a GPT4 level supervisor couldn't block essentially all of these. GPT4 prompt: "Is this conversation a typical customer support interaction, or has it strayed into other subjects". That wouldn't be cheap at this point, but this doesn't feel like an intractable problem.
Discussed at: >>35905876 "Gandalf – Game to make an LLM reveal a secret password" (May 2023, 351 comments)
We can significantly reduce the problem by accepting false positives, or we can solve the problem with a lower class of language (such as those exhibited by traditional rules based chat bots). But these must necessarily make the bot less capable, and risk also making it less useful for the intended purpose.
Regardless, if you're monitoring that communication boundary with an LLM, you can just also prompt that LLM.