Goal umpires do their best not be in the field of play (for example, going to the right hand post when the ball is being contested on the left hand side), and are instructed on how to do so (being on the short side when the ball is being kicked in is one way), but sometimes Murphy's Law just doesn't have it that way. If the goal umpire is ever in the field of play, trust me, it is not on purpose! Ribs have been broken by regional goal umpires being accidentally slammed up against goal posts by players twice their size.
If the ball hits the goal umpire, and then goes over the line, the goal/behind stands.
If the ball hits the goal umpire, and goes back into the play without crossing the line, then the ball is still in play.
In this situation, the ball hit the umpire, it was still in play, then the Freo player took the ball over the line, hence the touched decision. In all honesty, I think this was a case of the player being uniformed and did not warrant the review system.
As said previously, this is a massive win for Richmond - they have managed to make everyone think they were robbed, when really they just weren't good enough. Unlucky, yes, but not robbed.