It is that, but more. They are trying to tell The Big Lie again -- to make sympathetic military members believe that any order they might disagree with could be refused on those grounds.
It's their typical tactic of repeat, repeat, repeat, and eventually somebody believes -- and implements -- it. It's sinister, it's infectious, and it's a low-level attempt to discredit and overthrow this government.
Yep, you pegged the ulterior motive correctly. It’s the same tactic they use to surreptitiously motivate gullible, feeble-minded assassins.