Democrats are always less united after a Democratic presidency than a Republican one (think of the factional brawls between Eugene McCarthy and others in 68, or Nader vs Gore after the Clinton administration). This election will be the same.
These have been dry years for black political activists. Typically, presidents need them to connect to the Black community, and to get out the vote when needed. Obama doesn't need anyone to connect him to the Black community, and most Black people would walk through a blizzard to vote for Obama, so he doesn't need them much on that front either. Apparently one of the Seattle disruptors was so desperate for patronage that she tried promoting herself to the Republicans (yeah, good luck with that). Eight years of irrelevance is enough to make anyone hungry.
As I've pointed out before, BLM tried exactly the same stunt with Obama:-
It ended when some older Black people threatened to kick their arse for heckling Obama. For BLM, getting their arse kicked by Black people is not going to do their activist cred any good. Nor is heckling Republicans. A Republican would simply punch BLM in the face and be immediately rewarded with a 10-point jump in the polls. Consequently, these people are good for friendly fire and precious little else.
A socialist is as much a threat to a black nationalist as to a white nationalist. A black nationalist believes that life is about black vs white, and a white nationalist agrees with him. They might be on opposing sides, but they agree on the narrative. Its a symbiotic relationship, really, and if you spend any time reading black nationalist readings online you soon learn that they have a perverse preference for the white nazi over the white liberal.