Considering Makaveli wasn't meant for retail release and was going to be a mixtape it seems a bit odd that Pac would reach out to MJ for a feature as that goes against its whole anti AEOM, wack room beats, gritty, noncommercial aesthetic. For another project? Sure but even then Pac tended to use his tracks to help lesser knowns shine via their association with him as opposed to trend hopping or feature chasing.
Still, we don't know for sure but one thing I'm quite certain of is that
since we entered the clout chasing era people have become a lot more liberal with their tales about Pac and some of them are verging on being of the duck variety.
Not saying thats the case here but virtually every single person ever saw him in hospital, virtually everyone was about to do a project with him and virtually everyone was his ace.
Having said that hearing MJ on Makaveli would've been

and so unexpected whilst being in keeping with his own brand of duality.