Not even sure why the Fernandes thing was coming up.
The linesman grabbed Fernandes first for a start, somewhere around the elbow which actually is a place where if you grab someone you'll get quite a visceral response, particularly when they don't expect it. Try it on someone you're comfortable with. Wrists, elbows, a finger are pretty good places to grab someone and get a more dramatic response, it's instinctual because those are areas that from a primal point of view we want to protect because injuries are debilitating and take the arm out of commission.
Then Fernandes gives him the limpest push in response, not very forthright or aggressive, just petulant. Was still daft and something I would tell him off for as a manager but never a red card.
Really refs and players should be keeping hands off each other. Players should be keeping hands off at all times and refs should really be intervening with body position and posture to get in the way, mainly when breaking skirmishes up. The ref might have legitimate cause to be touching players occasionally but not the reverse. So that's why I think it's proper that Mitrovic gets a decent sentence for this, because I've seen it so many times at grassroots level. Refs turning up for peanuts to get physically confronted, abused etc. It's completely the wrong view to be seeing PL players aggressively pushing refs back.