@homegrown I understand that, but at the same time it seems so paradoxical. Mastodon is such an enclave of freedom on the internet and then some legal tug of war over the use of the name starts? It would be very sad, and probably a lot of people would then switch to the fork project. The name "ActivityPub" probably doesn't belong to anyone yet.
@michal
Safest option is just to avoid any trademarks.
If you're using a subdomain for a Fedi server, use generic subdomains like "social.example.com".
If you're talking about the network, call it the Fediverse, no one owns that AFAIK.