Valid points, for sure. But they can still make more roster changes after that and there will be injuries.
Every living, breathing pitcher is already on the 26 roster at this point. So the extra arm is probably Henriquez until somebody heals. And the only contender position player not on the MLB IL at this point is Carmago, arguably Julien. Possibly Keirsey if they want a PR type and he has to be added to the 40 in the offseason anyway.
Given how many injuries occur, I think it will still work itself out and nobody will get stiffed, so to speak.