I have no problem with the USA chants, when the crowd had to deal with annoying brazilian fans chanting "you're going to die" and "Brazil" all night. Except when their guy wasn't a favourite... In that case, they didn't seem to care.
Not that they had much to cheer for that night anyway
Also have you watched any of the shows that take place in Brazil? They boo everyone who isn't Brazilian, chanting really nasty things at them, etc. It is WAY more annoying than the occasional "USA" chant, IMO
As for Silva's legacy, I think it stands up to scrutiny as well as anyone's. Certainly way better than Fedor post 2006 (when Anderson started fighting in UFC)