Because of three landmark Supreme Court decisions the Army started letting gays serve openly, with one reservation, transgender had physical fitness issues.
Physical fitness standards typically do not fully shift until medical transition is complete. In many cases, personnel are exempt from physical fitness tests during transition. Because the gender transition process is unique for each individual — and not all transgender personnel will seek gender transition–related treatment — issues related to physical standards and medical readiness are typically addressed on a case-by-case basis. This flexibility has been important in addressing the needs of transgender personnel. (
The Implications of Allowing Transgender Personnel to Serve Openly in the U.S. Military, RAND)
In typical Trump fashion he is being the proverbial bull in a china shop. Just like when he said he was going to impose a ban on all Muslims, he is expressing a fundamental misunderstanding of the issues. I didn't really get the option in the poll so let me clarify, once they have made the change RAND defines as, 'sex or gender reassignment or gender confirmation.' I don't have a problem with it.
When I was in the Army it was my job as an NCO to council soldiers on pretty much everything. We had a gay guy in our unit, he was squared away and we talked openly about the legal and political things that were changing Army policy. Another guy one time that was assigned to my group had to inform me of a sexual harassment issue. Apparently the First Sargent had made some unwelcome advances and while deployed you would be surprised what a major problem this can be. It's not just gays, harassment and sexual assault plagued the Army early in the invasion of Iraq and the Army dealt with it.
I just don't think it's appropriate for them to be going through the transition on active duty. Once they have achieved the, 'gender reassignment or gender confirmation', I see no problem with it. Elective surgery is something the Army has little tolerance for, especially when it involves fitness. The military after long periods and lengthy deployments start to trim down the number of personnel on active duty, they simply have to scale back. One of the first things that will get you discharged is any medical or physical limitation of fitness.
I don't like how Trump did this but I understand some of the reasons the military has a problem with transgenders serving while they are going through the transition. There is one big problem though, the Marines for instance, when you have been discharged for medical reasons it's really tough to get back in. The Army isn't as bad but most of the ones who try go through a back door known as the Reserves and the Guards where waivers are more readily available.
In my very limited frame of reference I think a better policy would be to simply not allow those going through the transition to serve. Once completed, I really don't see a big problem for it although, the prescription medicine the need might be a big problem while deployed in a combat zone. The real issues are fitness and simple logistics, being openly transgender isn't really the issue.