Good question with no easy answer.

Would have to judge each situation on it's own merit.

In most cases I would not want to penalize the person who comes up with the ball if it was done legally.

If the stuck arm causes the stumble then a push it is.

My own opinion.

If it was almost a jumpball, it sounds as if they held the ball simultaneously. Then player A gains more control than player B, although player B still in the mix enough that his arm(s) is entangled with player A.

I can't help but think that a jumpball should have been called.

However not having been there, I can't make as good a call as you would, I didn't see how secure their hold was, nor how long they held the ball.