Mike and Arnold never had a rivalry. That's the first time Mike and Arnold competed in the same contest.
Arnold did criticized modern bodybuilding back in the 1990s , he attacked the way the guys dressed in the striped leotards and multi-print genie pants , Arnold actually criticized Sly Stallone in print as well for dressing like a clown with his full length fur coats as well.
He really didn't ' attack ' Dorian , he commented on ' This guy who is the current Mr Olympia The guy from England ' He didn't even bother to mention Dorian by name , he said he wins the contest and goes back to England not to be seen again until next year. He felt the current Mr Olympia wasn't doing enough to promote the sport like he did. Which was kinda of true but Dorian was much more reserved than Arnold but Dorian had a point Arnold was sorta out of touch with the modern scene he flew into the Arnold Classic once a year made an appearance and jettisoned off back to Hollywood.
Arnold never specially commented on Dorian's physique and it being the harbinger of the beginning of the end of bodybuilding. Arnold always gave compliments to others , Sergio specifically. The biggest slight is he didn't know who Dorian was or he did and decided not to mention his name.