The labyrinth doesn't have to be fast, and things like iocaine (https://iocaine.madhouse-project.org/) don't use much CPU if you don't go and give them something like the Complete Works of Ahakespeare as input (Mine is using Moby Dick), and can easily be constrained with cgroups if you're concerned about resource usage.

I've noticed that LLM scrapers tend to be incredibly patient. They'll wait for minutes for even small amounts of text.

That will be your contribution. If others join scrapping will become very pricey. Till bots become smarter. But then they will not download much of generated crap. Which makes it cheaper for you.

Anyway, from bots perspective labyrinths aren't the main problem. Internet is being flooded with quality LLM-generated content.