Lots to unpack here and I'll discuss further in this post. First of all, the game appeared to be getting chippy, so this wasn't just a random act. Miami was behind, they were upset that they thought Bam got fouled and was laying on the floor. Morris, trying to do the crappy NBA intentional foul took a beline to Jokic and didn't just foul him, he body slammed him. Jokic was trying to pass the ball up and it was a dangerous play and cheap.
Jokic reacted like alot of people would when you do a non-basketball foul intentionally and blasted Morris.
A couple of telling things in this whole exchange. Not one Heat player came to Morris's defense, at least not initially. Yes, it looked bad, but Morris is a banger and he gets hit all the time. He "soccered" it up a bit by laying on the floor and going back down. Did a great Lebron imitation.
Now the big picture and I don't know why the NBA does this. But they have this open path rule and it's just a bunch of crap. If a player fouls a team who has an advantage, it's intentional and the offense should get two free throws and the ball back. This would stop this silliness. I'd even be ok if the play continued - like soccer or hockey then assess the penalty when the offensive possession is over.