It can be just as true for LLM output. One can use LLMs simply in a way to gather information, replacing Google by a much better one, and create lesson plans yourself based on the information provided. Nothing stands in the way of you doing that. Just like the many devs on this website who basically use it as a StackOverflow to ask questions to rather than "give me the full code of the solution" and just blindly copy-pasting that in.

LLMs with web search enabled also give sources.

There's not much reason to believe LLMs are incapable of outputting a similarly well-structured lesson plan as those provided by third parties. It fits well into what they're capable of.

The problem is, again, that the teachers in question clearly don't care about the quality of their teaching in the slightest. Are LLMs a tool that could amplify their awfulness further? Sure, but at the same time they can amplify the goodness of the hopefully larger group of teachers who do care.