There is one thing you can't do and that is reason with deluded people. A player missed pre season and you expect him to play games?
Its a new manager, he has new principles, ideas and how he wants to play. Players like Martial who had good pre seasons buying into what the manager wants for what? to be dropped for someone who is not bothered?
That is the first issue, which Ten Hag is right.
Secondly, this argument of he hasn't played games is false, he started against Brentford and almost every Europa game. We have not just not won a game, we haven't scored a goal when he started this season.