Indeed they could. But Matthias may not have time to help the BuddyPress devs right now. That ticket has remained stalled for 5 months since the comment that asks;
“Can you share more about this? Maybe some links so that I could educate myself of what this is and how BuddyPress can help.”
Which suggests that a couple of quick comments and links from someone else might help. Something like a link to the Guide for new ActivityPub implementers, a link to Matthias’ AP code, and a suggestion to create an account on SH and ask questions. Enough to help them get started. Then they can dig into Matthias’ code for inspiration as they go, and ask him (or SH) questions if they get stuck.
I just tried to do it myself, but I’m having problems logging in to WordPress.org.