By AI guardrails they mean: AI cannot be used to write or rewrite scripts, and cannot be source material; but writers are free to use it if they wish. Reminds me of how elevators originally had operators, until everyone realized how wasteful and silly it is to have someone whose sole job is to press elevator buttons. As AI improves, we will come to feel the same about writers.
But at this very moment, AI generating anything suitable for something other than SEO blogspam isn't possible anyway. It might be right around the corner, or it might be "right around the corner" like self-driving cars were in 2015.