The "Commander-In-Chief" is at the top of the ladder. Disparaging comments regarding your boss, public or private, is likely to get you fired in any job you hold, not just the military, if they become known.
You can, and should, share concerns you may have, but sharing a concern about, say, whether or not using the military to assist ICE and ERO is allowed/constitutional is quite a different thing than saying your CiC is a fascist, racist, misogynist, moron.
Now, Charlie Kirk is not a military authority in any sense of the word, but a member of the armed services can't go around acting in a way that is perceived as being only interested in defending the rights of certain segments of the society either. The US armed forces are there to protect this Union and its citizens from foreign or domestic threat. Not some of the States, not some of the citizens, all of them and all of us.
Any statement which might bring the fidelity of a member of the armed services to that mission into question should be scrutinized. A member of the armed forces who believes that political assassinations are sometimes justified might just be someone willing to perform such an act themselves, and such a person is not fit to serve the citizens of these United States. Fidelity to civilian command is the hallmark of our military might, we don't have coups in this Union, we have elections.
