Are fees only included in the message thread with the host but NOT in the Listing info or Rules enforceable? [FL]

Booked a large house for 5 guests for 4 nights over the holidays. Had 8 guests 2 of the nights for Christmas.

There is nothing in the Airbnb listing that mentions guest fees.

There is nothing in the house rules that mentions guest fees.

After booking the host sent some info on their guest fees in the message thread.

A month after the booking was completed they sent a request for $500 for extra guests.

Is a fee schedule that is only included in the message thread enforceable? I didn't agree or acknowledge their messages about the guest fees when they initially sent them.