Some screeners have a bad attitude regardless. But yes, most escalations I have seen are due to the passengers attitude. I have some screeners that are cheerful and happy no matter how rude a person is to them. I give them credit for that, I don't always understand how they do it.
It is irrelevant who has the original bad attitude. The screeners work
for the public, and if they can't deal with passengers with bad attitudes, they need to find another line of work.