Your second reason is THE reason.
Your first point is a precursor for the second.
You need commanders and military members whose consciences are already seared in order to fire on civilian “resistors”.
What is the percentage of ‘senior officers that have been purged’?
The military is being prepared to fire on Citizens, but when it comes to it, the military is much more apt to be distracted by a ginned up foreign war or will just be all shipped out of the country while the HS/FEMA army implements the Socialist Solution. Leftists do not trust the formal military, no matter how much they have warped and purged it.