I just had to register when I saw this.
It is 100% safe... Revolution is wrong.
I was sitting above the Milan "ultras" and everything around me was red. I was at the game Ac Milan - Real Madrid and was wearing a Milan scarf but both of my friedns were wearing Real Madrid jerseys. Nothing happened a few fans smiled at them and asked me if I am a Milan fan then high fived.
Only infront of the stadium one Milan fan said to my friend bastardo
When Real scored both of my friends were the only two people cheering like crazy and nothing happened.
You have nothing to worry about.