Partly about the budget bill and his concern he wouldnt get all the $$ he was asking.  Vicky Hartzler and her ilk raised questions about the costs of transgender service members' medical costs (estimated 8.6M per year, 0.001% of the military's healthcare budget) and that taxpayers shouldnt pay for ''surgeries" and he just figured he'll just ban them from the military.  This of course was not their intent but of course you now have the xtian right and people like hartzler agreeing with the ban.  BTW viagra for service members cost ~42M per year and it is estimated that 45's weekly jaunts to his golf courses will cost U.S. tax payers 60M this year.