Lebron lost his cool. He missed a shot beforehand and the Pistons were winning at the time, so Lebron was frustrated and then Stewart boxed out aggressively and Lebron just threw his arm in the general area of Stewart's head/upper body at the peak of his frustration.
Pretty sure he thought "I'mma throw my hand at him and see what happens wherever it connects".
And then he tried to play it off as nothing serious when he realized he literally punched him near the eye.
So yeah, I doubt Lebron was aiming to draw blood, but he surely was aiming to take out his frustration on Stewart, so it was intentional in the sense for sure.
So people saying that Lebron was just trying to free himself are delusional, but people saying that Lebron viciously tried to do serious damage to Stewart are also delusional. It was just a reckless attempt to release his frustration, which should warrant a 1-game suspension I believe, nothing more and nothing less if we're looking at the similar previous cases.
And when it comes to Stewart, I don't know what to think, is it a pure loss of control or simply a calculated attempt to retaliate?
He looked out of control, but then he was composed enough to put on an act that he's cooled down so that people would stop holding him tightly so that he could go run at Lebron again.
So I think it's an ego thing with him, he simply doesn't want the end result to be that he took more beating than he gave. And that's a pretty dangerous standard to try to live by.
I think the league will suspend him for some time, but I personally would give him 1-game suspension and I'd order him to see a professional for this.