It doesn't have to be enforceable. But as soon as you do this, any potential hiccup like having to evict tenants or go to court for anything minor, and the state/police find out about your little "unenforceable" violation.

People on AirBnB generally are not 'tenants' and kicking them out is as easy as trespassing them, optionally with a Sheriff if they refuse to leave. You're reading way to much into Sheriff Bill worrying about what's happening. The AirBnB side is typically a civil matter.