I think you would agree that harvesting that information is far easier if it's being literally POST'd to your servers (which ActivityPub does) than if you're going out to scrape them, no? It's the same principle with defederation; either they're going to scrape all the data, or the data is going to be literally sent to their platform.

The point is, the idea that "don't use threads" solves the problem being presented (your data being harvested), is wrong.