How about if you put that notice on the website, but also write it out explicitly and post it via registered mail to the Meta lawyers. Explicitly state that the content on your site is not licenced to be scraped for free and any usage must be paid for (eg $10/GET with penalties for non-payment), and that any usage of the site by Meta or their agents is an indication that they accept the terms fully.

Then check your logs and start sending appropriate invoices.

Then after 1yr of unpaid invoices: <profit>