The term "nationalist" is used pretty loosely by most. The dictionary definition is pretty benign in my opinion, and would not match how the far left or right might define it. I'm not a Trumpist, but I think his use of it was actually pretty appropriate.

I personally don't support everything this country does, but I think it is absolutely toxic to think that simply having some respect for the flag, or "flag worship" is "disgusting." Governments can be terrible, sure, but national symbols (like the flag and constitution) stand for much greater things, and should be looked at apart from our often corrupt leaders.