This whole thing is a prime example of how not to use government email, a pox on all their houses. Number one why does a Major in an operational command have the time or patience to compose that diatribe a simple "no we are busy defending democracy" would have sufficed. If he felt that strongly about it make a call to someone he knew at USAFA.
This email was not intended for public consumption and is probably making mountains out of mole hills but there are many things to be learned from it.
Never get into a pissing contest in email. There are things people will type that they wont say on a phone or to your face. If you have a disagreement with someone or their email (this happens to me often) pick up and go see them in person, if you are the senior one, have them come see you in person. If this is not possible pick up the phone, not there wait. You cant win an email pissing contest, and you have no idea who is either BCC or forwarded your messages.