That she is.
I once told a Sergeant that the Commander-in-Chief, President Lyndon Johnson, "was a low down dirty S*n *of a B!tch"! He agreed and said I was in the majority and to sling arms and continue to march.
However, I think this is going to work for her. A "dishonorable" is not far away, or a "general" on plea.
A more appropriate action on the sergeant's part might have been to suggest that you keep your mind on your duties.
During off-duty hours and especially, though not absolutely, when out of uniform, a soldier has a right to free speech which has not been given up by taking their oath of enlistment.
Soldiers vote, even when stationed overseas and on duty 24/7. Criticism of the US Commander-in-Chief, who is an elected civilian, would be tolerated as long as it does not affect performance of duty. One of the most "disrespectful" times I recall in service was watching "Laugh-In" while General BullRight was on. The day room, where the TV was located, was completely full.
One of the benefits of an all-volunteer army is that the average level of satisfaction with national policy and military necessity is much higher than with a force populated by draftees and those who have enlisted to avoid being drafted.
It should be a source of pride that our military functions well because of its soldiers' sense of duty to country (the Constitution) and not just because they seek to avoid punishment.