That's a very narrow view of data scraping, there's lots of ways to get data.
The Fediverse is built on ActivityPub, which is an open protocol that's designed to broadcast data with no limitations or restrictions. If you don't want your data to end up in the hands of anyone who wants it - including those nefarious AI trainers - then that's an inherently incompatible goal with ActivityPub.
If you're just worried about specific instances being overloaded with requests, then sure, all the usual rate limiting DDOS-prevention Cloudflare tricks will work. But the data itself isn't "protected." Someone who wants it could simply run an instance of their own specifically to collect it.