Yeah, that's the main gist. DoD is straying from their lane because Hegseth is a raving Christian Nationalist, and not even one of their better advocates, and that is a LOOOOOOW bar. This all stems from a published list, screenshot in the article, that still includes Mormons but doesn't preface them with "Christianity" like it did for the others.
I wouldn't be surprised if he personally redlined a Word doc to delete "Christianity" from the Mormons' line before approving it for release, and maybe without any particular emotional animus, just parroting what he remembered from Sunday School that one time he wasn't hungover. The fact that the Jehovah's Witnesses and Adventists made the cut might also argue for there not being a ton of theological rigor to the decision.
I think Mormons get too defensive about wanting to be included in other Christians' theological definitions of Christianity (literally can't happen... The Mormon Trinity is polytheistic by almost any standard, to say nothing of extra books and other heterodox beliefs), but those invested in one group or another's theology can overlook that there are other contexts (shared history, cultural practice, self-iidentification, etc. etc.) that can generate just as much passion and be internally reasonable. It's almost like the separation of church and state is a pretty good fuckin' idea, especially in a pluralistic republic....