I don't know how can anyone not side with Amorim on this. He separated Rashford from the squad, to protect/implement the group’s culture and discipline. Letting one player bend the rules, no matter how big their name is, can and will cause issues with team dynamics and set a bad example.
Amorim’s showing the squad that no one’s bigger than the team, keeping things fair and focused. It was intended to give Rashford time to refocus and come back stronger, but instead Rashford decided to do that interview which leaves Amorim no choice but to keep him sidelined.
Rashford is a player that believes he's better that he is. The thing to do was train hard, get your fire up and start showing some fight on the pitch, even if the performances don't came up good don't let anyone ever question your effort and desire.
Instead he choose the victim card, which he's used many times before. "Don't question my attitude because you don't know how many busses I took as a youngster to get to training" or some poor excuse like that. Really show just how mentally poor he is. The "we're part of the 0.01%" with Lingard as well. Showing "we've made it" when they were part of the poorest era in Manchester United modern times. He has a rotten mentality, acts as if he's got nothing to prove when he's achieved nothing worth mentioning.
I hope he never plays again for us. Set an example for everyone now and for the future, no one is above the team. You don't train hard no matter if you're an exciting academy product like Garnacho or the face of marketing like Rashford you won't even be selected. That's the way to raise standards.