I would say it's generally a mistake to attribute to others what would be our own reasons for doing a thing.

Besides having appeal to those who truly wish to serve their country, the military can be appealing to authoritarian personality types, to lovers of government, the bigger the better, and to those who love having the government as their daddy, providing guaranteed paycheck, healthcare, and pension. These types do not necessarily have any objection at all to leftist government and can even prefer it.

Colonel Aquino was a Satanist, for example. He fit in just fine in the military. How is that? It is from top officers widely not being as clean as we would truly like to imagine.

Or, remember the recent Pentagon child porn scandal? All that CP on computers all over the place in the Pentagon? How many arrests were there? Is there any evidence anyone even lost their career?

Again, to me the thing to hope for is a specific part of the military being clean Patriots, rather than speaking of the entirety as such.