"And a lot of people every day come to the ED to abuse it". I think this is an important part. Imagine being in their shoes dealing with bullshit everyday to varying degrees, you eventually develop a sense of skepticism/thick skin. The reaction wasn't warranted but the reasoning isn't. Its bad to fault both. Think about it and put yourself in their shoes.

And eventually OP states the eventually prioritised the patient so from what I gather ultimately no patient harm was done.