No one is guaranteed anything, but there's a reason he was nailed on to be no.1 at the start of last season.
Once he replaced DDG. Over all the team had it's best defensive record for years with him in goal, finally got under the average of conceding a goal a game, down from 1.5. Kept more clean sheets on average than at any point with DDG over the last 4 seasons. And went from having a win rate of 50% with DDG to almost 70% without him. He was also better than DDG on almost every metric individually.
He might be an arrogant so and so, but all the stats show he was better for the team overall than DDG has been for years. Yet, somehow he never showed anything that suggested he could be no.1 at Utd. I find it all very odd.
Again, he was not nailed on number 1, DDG was playing Europa league games, including the final. So clearly, he was not nailed on.
Yes, the keeper is the only reason we concede goals, if that is the case, lets see him keep that 1.5 goal a game at Nottingham Forest.
Like he made no mistakes? SU away, Liverpool home. There was 0 evidence that he was better than DDG by the margin you are presenting. Lets see Nottingham Forest win rate with him then.
Also, he was told he will be first choice, he got covid and lost his place, we can't blame him for getting covid but its justifiable to blame the club.
Secondly, DDG started the season in fine form, big big saves at Wolves, West Ham etc... which then led to Ole's job being under pressure, you think a manager who needs results cares what an arrogant keeper thinks when he is trying to save his job?
Finally, Rangnick came in and gave everyone a chance, he clearly didn't fancy Henderson and his attitude. Not 1, 3 managers including Carrick stuck with DDG.