It takes lots of guts to take over a team that's actually playing win one game, draw two games and lose three games before winning again. That was the situation Manchester United found themselves and Amorim left his winning Sporting side in Portugal to England to catch a depleting team. That's enough guts for me, yes the team ended up badly but for the benefit of doubts I personally didn't judge him because he didn't start with the team and didn't also buy the players.
I was literally thinking of a stronger word than "guts", but let's stick with that first. Rejecting a job from a big club Manchester united is literally a difficult thing to do. Amorim had to seize his opportunity, which I believe any other manager would do. Just like you've said, I didn't blame him for having a terrible season despite the pressure and difficulty that was left by Ten Hag. He has had a taste of the Premier league, so I believe he must have known areas to work on.
Looking at his relationship with some players last season, this is the best time to decide who and who not to work with as there might not be excuses when the season starts. Amorim has what it takes to do well, but the big question is if the club would be willing to give him the time to do it.