Everything he has said is 100% correct.
When United won the Europa League they were literally odds-on favourites for every match that they played, and exclusively played against much smaller clubs who had spent far, far less money on their playing squads.
Arsenal narrowly lost to Atletico, who have been in the Champions League final, knocked Barca out of the CL twice, and won La Liga recently, who have one of the most highly regarded coaches in the world, who have possibly the best defender in the world in Godin, one of the world's absolute top players in Griezmann, and countless other world-class players, and who are at least as big as Arsenal as a club. Arsenal had a chance in that tie, but were second favourites, and Atletico would have fancied their chances against any English club; they've played Chelsea 5 times in recent years, and won 2 and drew 2 of them.
That's not being biased, that's just reality.