Weight and shooting straight are things that can be changed. One's sexuality cannot. Your post is asinine.
People who are twice their ideal weight will be disqualified until such time that their weight is in line with what it should be. If someone can't shoot straight because they have bad vision they can't necessarily do anything about that either. Wearing glasses only works so far because if you lose your glasses in a combat situation it's not like you can just excuse yourself while you get a new pair. Sometimes people can't shoot straight because they are just not very well coordinated - you know, some people are just plain clumsy.
Sexuality isn't the same as gender identity.
The brutal truth is that the military is about combat effectiveness. Nothing more and nothing less. Anyone who requires special accommodation isn't going to fit in, whether that "special accommodation" is a daily shot of insulin (which can't be guaranteed in a war zone), daily hormone injections (likewise) or whatever else. If your presence diminishes combat effectiveness you can't be there. The military is there to fight, not to endlessly change and fit in this or that special case.
It doesn't work to say that asthmatics and diabetics can be excluded because of the special accommodations they might need but those in the process of changing gender are somehow special cases and have to be accommodated whatever the cost. There may be a case to be made for those who have completed a transition to be allowed to serve but if the presence of such a person would diminish the overall combat effectiveness
Edit: Not sure what happened to the last part, the final sentence should continue with "they must be excluded just like anyone else who diminished combat effectiveness".