"On the other hand, the US Military needs to be focused on the mission."

Which, by focusing on fighting stuff like this, they neglect.  Good piece in The Globalist on how the US military is producing leaders who are good on tactics (and self-puffery) and useless on strategy.  The elimination of people who want to serve (but happen to be transgendered) also means more challenges in recruitment and retention.

But either way, you're talking as if this policy change were based on some objective assessment of the effects on troop morale, rather than just cheap partisan advantage....