Yep. I told a few of the guys here who were planning on going to this match the same advice, if they're going to sit with Inter fans it's generally completely fine to wear Juve colors as long as you're not obnoxious, I really doubt they would have ganged up on that guy completely unprovoked. Moreover, he was seated really close to Curva Nord, you can see CN guys that climbed over the barrier & into his section, so he probably did taunt them or something. If you manage to piss off ultras you would get the same treatment at any stadium in any city (especially in Italy), it's not just limited to Inter.
However I don't condone physical violence, it's really beyond me why someone would feel the need to injure or even kill someone because of the club they support... much less needing 20 guys to do the job. Disgusting behavior no matter who it's from, just yell a few insults at him & move on.