The dsm v is a great tool but there is a reason there are multiple issues of it. denotations change. The lgbt population was once in the dsm. They no longer are seen as having a mental disability. Women who worked outside the home were once classified as having mental problems. If a person identifies as transgendered and joins the military they should not be held as demented or deficiant. I have meet transgendered veterans and there is not a doubt in my mind that they are exactly of the mindset to fight for this country.
The issue is that instead of fixing the issue, accepting them once they transition, the focus is on a temporary diagnosis. This diagnosis falls away post transition. It is curable.
Unless you feel that all menopausal women or men with to low testosterone should be kicked out of the military, this idea of the trans community not serving does not make sense. All three of those populations may use hormones to help their conditions.
Inter-sexed individuals could also be forced out of the military. It is estimated that there are more inter-sexed people than left handed people. Should they be denied the opportunity to serve? What is happening now is such a scary and slippery slope. If my uncles were truthful the military breaks everyone down to the same level no matter where they came from what they look like so that they can built up into a unified force. Save for any true mental illness the right to serve is still theirs.