Alternatively it could be a pretty predictable move given the interests of the Department of Defense, to even quote the article you cited, [@Penny].

[quote=BBC News]The Department of Defence (DoD) had submitted a report to the president which said allowing those with a history of gender dysphoria to serve entailed "substantial risks" and could, by exempting them from existing physical, mental and sex-based standards, "undermine readiness... and impose an unreasonable burden on the military".[/quote]
[url=https://media.defense.gov/2018/Mar/23/2001894037/-1/-1/0/MILITARY-SERVICE-BY-TRANSGENDER-INDIVIDUALS.PDF]There is even a lovely official memorandum for reference on their rationale.[/url] It does even contain things as the following recommendations to, and I quote, to [i]specifically[/i] "retain" a selected set. To borrow from another source as well, just in case both of those examples were not enough and that somehow the official recommendation was insufficient;

[quote=Newsweek]
The White House said Defense Secretary Jim Mattis had found that individuals with a history or diagnosis of gender dysphoria presented a risk to military effectiveness.

“This new policy will enable the military to apply well-established mental and physical health standards ... equally to all individuals who want to join and fight for the best military force the world has ever seen,” it said.

In a memo cited by CNN, the Pentagon said that Trump's order would exclude those "stable for 36 consecutive months in their biological sex prior to accession," servicemembers who "do not require a change of gender" and troops who started serving under the Obama administration's removal of restrictions on transgender recruits. [/quote]
But yes, let us appeal to emotional outrage and feelings in military matters. No way that can possibly go wrong, mixing social progressivism in an environment that does not particular care about it. Certainly the sort of commentary and analysis one would expect from a "trash" administration. For the record, the lengths they speak to in the memorandum about unit cohesion and mental health hit the most close to home; probably the best thought based arguments in the document over the obviously physical ones.

As a later edition to my post and to state the core of their mindset, directly from the source.

[quote=Memorandum for the President on the Subject of Military Service by Transgender Individuals]Moreover nothing in this policy should be viewed as reflecting poorly on transgender persons who suffer from gender dysphoria, or have had a history of gender dysphoria, and are accordingly disqualified from service. The vast majority of Americans from ages 17 to 24 - that is, 71% - are ineligible to join the military without a waiver for mental, medical, or behavioral reasons. Transgender persons with gender dysphoria are no less valued members of our Nation than all other categories of persons who are disqualified from military service. The Department honors all citizens who wish to dedicate, and perhaps even lay down, their lives in defense of the Nation, even when the Department, in the best interests of the military, must decline to grant their wish.[/quote]