He didn't really say Martial and Rashford are cry babies in this quote though. He was asked how players should deal with managers' criticism and he said this. How do you know this is targeted particularly towards both ? Maybe they were also tough and dealing with it normally and he didn't point towards them. Maybe he was talking about himself. Nothing really to be mad about this quote. I don't they both cared about it or took it on themselves.
As for his agent, it's his way. Look at his quotes about Pogba last summer.
Finally, this fitness state thing Mata shared on his account and joked about it. Is Mata a twat for doing that too ?
Really, all these aren't good enough reasons to label him a twat and take the hate towards him to a near personal level from some. Guy is a nothing player for us. He played 2 years and won nothing. He didn't like it here, couldn't handle the pressure from fans and media and decided to move on. Hardly anything to get mad about, imo. 1 year after he left, pretty much time to move on and forgot he even existed for us.