I am pretty convinced many "forward" passes as spotted by fans are actually fine.
But this one looked pretty forward to me. There may have been some momentum but on a one or two step lead up it would have been limited.
It was a tough call for Warriors fans.
As Gasnier on the coverage and some Sharks fans have said, it "makes up" for "losing" to a forward pass the game before, but that is only for the Sharks. It doesn't help the Warriors at all (or other teams like the Tigers and Raiders who are trying to take their spot, or the Broncos, in the 8).
But in all close games, any number of mistakes, bad calls or fluke plays can change the game.
Warriors were called for milking but Prior got penalised anyway, and Warriors got their field goal off that set. Could easily have been the Sharks getting a set at the other end instead (just one example, plenty of calls and non calls went either way that could have gone the other).
Sharks may have kicked a field goal or scored in the last 4 minutes even if the pass was ruled forward, so the non decision didn't completely seal the Warrior's fate, but it didn't help.
It is hard to say the "better team" won anyway. Warriors started much better, Sharks were all over them through the middle of the game, and it was pretty gritty from both teams at the end.
I can understand Warriors fans feeling robbed.
In reality, both teams had their moments, had some good plays and some bad. Both look likely to make the 8 and will want to improve to seriously threaten.