Thats diplomacy for you. It costs nothing to be polite.
At the same time his faux-outrage over "saluting an officer of a country that killed 33k us servicemen" is rather droll as by such logic he shouldnt be talking to Germans, Russians, Brits, French, Spanish, Chinese, Japanese etc. etc. It would seem whoever this tweeter is he needs to get a sense of perspective for geo-politics.