It is necessary to 'stand up' to boorish behavior when you are the target, you have little other choice, it is easy to stand by and hope or think that someone else should intervene and neither fanbase is immune to it.

I shared in another thread about walking to the game Saturday and have a couple of BYU students get in my 75yo Patriarch father's face and ask him if he was drunk already, it was really aggressive and intimidating. I had to step between them and my father and say to them, "Drunk eh? He is a Patriarch you morons..." They backed down after that. They were among a group of about 50 others (I assume part of the 'ROC' or whatever that was) who did nothing to address their boorish behavior, and frankly I don't blame them for it.
(Sidenote the staff at the HC were having a hard time getting them to stop blocking the pathway.)

I had to react because it affected me directly, I wonder if I would do the same if I saw it as a passerby instead. We all have fantasies of noble behavior but the truth is most people probably won't intervene, particularly if there were people closer or who I thought in a better position to do such. So with this excuse of, "No one did anything..." we are all guilty of and has been well studied and documented as human behavior.

If you don't believe me, no BYU fan intervened when a guy spit on my buddy at LES many years ago. I'm sure there were many who were upset about it, but again, nothing was done.

If you don't believe that I'll tell you about the time where I was witness to a massive accident while waiting on my bike at a stop light. I put my bike to the side and tried to get out to the intersection to help the lady who was hemorrhaging badly from here head and had people honking their horns at me upset because I was getting in their way of passing by a massive accident.

But these are the actions of the individuals and I get why people think that other should intervene, but the truth is most all of us don't do it ourselves.