my father has been a ref his whole life , it wasnt an obstruction , if your talking about the tackle inu did from behind cherry evans , balin did not run behind cherry , nor did cherry change his direction to impede a player , when a player makes a play to a tackle from behind like inu did these are the only parts of the obstruction rule that comes into play.
also if you rewatch it inu tackles cherry on purpose to stop balin passing him the ball and should have been a penalty to manly.
the refs missed alot of stuff mainly in favour of the warriors , for example the warriors first try should not have been awarded due to one of the players pushing cherry evans over as he played the ball preventing him from tackling the dummy half who ran five metres before offloading to johnson.
an insanely bs call was the no try call against foran who clearly scored yet bias video ref hits the red button , after watching the replay six times it was clear to anyone who knows the rules that it was a try.
the refs missed some calls against manly aswell for example watmough getting up n playing the ball sideways , jamie lyons very clear strip , which was argued by the captain of the warriors to no avail.
n im sure they missed a few other things of which i cant clearly recall right now.
with all that said though i can assure you there was only one obstruction in the whole game that went uncalled and it wasnt by manly :)