The argument shouldn't even be here if they truly saw the performance of both teams in that particular game, the record is there and the game statistics don't lie, Inter Milan dominated the game they created more chances and took the lead but they gave it all up when Milan took advantage of their attitude to counter attack them to score those goals. Milan won the game at the end of the day but Inter Milan played more better despite losing the game by the end of the day.
Inter Milan got a shocked defeat even they played well in most time of the match but it's unfair to say AC Milan don't deserve this win. They played well to avoid a collapse after conceding two goals and equalize the match before scoring a winning goal in injury time. To do all these, AC Milan must play well and be strong mentality as well as have ambition to win this match even it started not too good for them.
I don't know if there will be chances for Milan in the domestic league but until that happens I strongly believe that SupperCopa that has been crested in their name should be their only trophy this season looking at their performance and current position in the league.
AC Milan still have a half of season to improve and chance to join top four is small but it's not like impossible for them now. They will try to play and improve their performances and if they won't end this season in top four for Champions League ticket, a ticket for Europa League next season won't be too bad for them. They won't get that ticket too if they won't try hard, because there are many clubs are competiting for top positions in Serie A.