I’ve seen the play several times, and I still can’t tell with certainty, if the ball went past the net. For a field goal to count, the ball has to go through the net, and not just past the rim. To me, that shouldn’t have needed a review by Houston, and that whole 30 second rule wouldn’t have even come into play. A play like that should be like the refs reviewing a three point attempt during a stoppage in play, to see if the player was beyond the three point line.
BTW, Harden’s real time reaction to “missing” the dunk probably didn’t help matters, as he immediately ran after the ball as if it was still a live play.