Nothing about ActivityPub is specifically "twitter-like". In fact the protocol itself, if anything, is way more facebook-like than twitter-like (and largely derives from the facebook-like pump.io). It just so happens that the largest implementors are Twitter-like. But that's not reflective of any protocol restriction. https://news.ycombinator.com/item?id=16836027
We also designed the thing *so Diaspora could adopt it*, even though that didn't happen.
@cwebber I think an appropriate short term solution is an adapter