Exactly. It's just an insult to them.
A while back, one of my Trumper neighbors decided that she didn't use an elliptical work-out machine that she had bought over 2 years prior. She took it back to the store without a receipt and demanded that they give her money for it - not just store credit - even though it was well past the return date.
When telling me this story, she acknowledged her crazy behavior by saying "haha I was acting like such a liberal."
In her mind, it's as simple as "liberal = bad". The actual definitions of words mean nothing to them.
Plus, Trump tweets in all caps. Not because he's angry all the time, but because he's old and that's the only way he can read the characters as he types them.