Couldn't agree more.
As commanders we lead a team of individuals who've proven they are qualified for the job. It is our duty to safeguard the integrity of the team and look out for every single crew member. Regardless of sex, race, colour, sexual preferences or religious views.
Rainboe is entitled to his opinion. And so are people who have problems with people who change their gender. You are free to argue your point of view on a forum. But once on duty you must put your personal views aside.
People who are unable to do that should never be put in a commanding position. For the ability to unify, motivate, encourage are traits that are vital to have in order to perform as a leader.