If you don't like politics, stop reading. For those who have to live in this world...
Anytime a politician or those in power target the poor, the powerless, minorities, and those who have no means of defending themselves, then take a close look because they are most likely either looking for a scapegoat or trying to deflect and distract from something else.
No-one should be singled out based on gender, sexual orientation, religious choice, race, socio-economic class or anything similar. Any country that is diverse in its population and works to integrate, not separate, will be stronger because of it. Moreover, a country that looks after the weakest of its citizens is a society that will be just to everyone.
Authoritarian regimes get their start with scapegoats from small groups outside the mainstream. We should have zero tolerance for any such discrimination from our government. The recently tweeted 'trans ban' is exactly such an action. If someone meets the physical and mental requirements for the military, or any other role, they should not be discriminated against.
As an example you have likely already seen, I give you Kristen Beck, a transgender Navy SEAL. Kristen seems like exactly the type of warfighter we want, and wouldn't let things like 'bone spurs' get in the way of serving. Her quote sums up the entire situation perfectly:
It's a leadership issue, not a transgender issue.
America is better than this, and such divisiveness can't be allowed to stand. What is happening right now is not normal, and we can't allow it to become that way. To those who don't care about such people, let me make this pretty clear - Donald Trump doesn't care about you, or your tax cuts, or your coal mining job, or whatever you thing you can get from dealing with the devil, and one day you will be the target, no matter how white or male or Christian you are. Defend the little guy, and you're defending yourself.
Oh, and it's just the decent thing to do.