[evanprodromou]

That's probably a fair consideration. I and others worked on an intermediate system called pump.io, and the ActivityPub interface is very similar to the pump.io client-to-server API and federation protocol.

The biggest advantages of ActivityPub over OStatus are: JSON instead of Atom XML; a defined client-to-server API; and private distribution, including to contact lists (like Diaspora's aspects).

As someone who has worked on this type of standard for over a decade, I can say that it's the best federation standard I've ever seen, and I've seen them all.