Does it matter what he thinks?

I don’t understand what his relevance is here.

The world has plenty of countries where the military decides who gets to be the President, to sit in the legislature, to serve as a judge, etc. Or maybe a group of senior military officers rule the country directly.

In quite a few of those countries, a "top reason" for the military seizing control was that the (civilian) political process became profoundly dysfunctional and/or violent. Claims that civil war and/or widespread anarchy were imminent (or worse, before the military stepped in) may have plenty of solid evidence behind 'em.

My impression is that the U.S.'s top (military) brass really, really wish that no such situations occur in the U.S. At this point, I'd guess that they have a fair number of ideas, for "all our choices are horrific" scenarios. (But few of those openly discussed, and ~none written down.)

However dull Gen. Milley's statements in the article might be, I'd say there's a subtext - along the lines of "Dear idiots and troublemakers, do remember that the U.S. military does exists, and will for-sure be profoundly unfriendly to you if you cross certain lines."

For now, and we need to keep it that way, though it's unclear how apart from every class and interest group serving.

Your statement is why I asked.