vidal was inactive and out of play so it should have been considered as offside anyways no?
no, Vidal was still in play, covering a potential offside on Muntari:
"Any defending player leaving the field of play for any reason without the
referee’s permission shall be considered to be on his own goal line or touch line
for the purposes of offside until the next stoppage in play"
Page 103 - Infringements
Juve also got a a goal disallowed but Milan going 2-0 up would have given a very different complexion of the game and most likely decided it in their favor - very poor decision by the linesman who clearly had a very good view of the situation and didn't look that diff to judge anyway. Also the ref seemed to point to the circle as if he called the goal but seems to me he was mislead by the linesman and changed his mind.
Anyways, with all the absences of key players for Milan, a draw is not a bad result for Milan even if a win would have been sweeter even if not decisive at all. Everything will be decided in the games that are left to be played.