Obviously it wouldn't be allowed in this community, but how feasible would it be to make a community on a friendly instance and start shipping data through it somehow? If it works for NNTP it ought to work for ActivityPub, right?

Potential problems:

1. Community full of base64'd posts immediately gets blocked by everybody's home instance.
2. Community host immediately gets sued for handing out data it might not have a license for.
3. Other instances that carry the community immediately get sued (see #2).
4. Community host is in the US and follows DMCA and deletes all the posts that are complained about.

Maybe it would work as a way to distribute NZBs or other things that are useful but not themselves copyrightable? But the problem with NZBs is you have to keep them away from the people who want to send DMCAs to the Usenet providers about them, or they stop working. So shipping them around in a basically public protocol like ActivityPub would not be good for them.