Ooh, they are on the Fediverse too!
Shout out to the other co-chair of the Social Web working group @tantek.com , and the co-chair of the Social Web incubator community group and contributor to several Social Web specs spec @aaronpk !
Everyone who directly contributed to #ActivityPub are listed in the acknowledgements of the standard: https://www.w3.org/TR/activitypub/#acknowledgements