You are probably correct. The military can't make its enlistment quotas, and U.S. Army trannies who can't pass the physical fitness requirements get a pass. So, it's up to the reservists who still have time on their enlistments to stand before the cannons loaded with grape shot.
The Fox News report on the call up refers to “support troops” but not combat units, so my guess is that none of them will be facing grape shot or any other kind of cannon or gunfire.