He was glad that something as stupid as this is now put behind them because he was baffled at how.. let's just say, persistent she was. Now, she is asking for an explanation as if she had deserved any in the first place when he asked her to scram. At this point, he wasn't sure if it was her self-entitled heroism or because he acts like a piece of shit to her that it is mandatory to tell her everything she needs to know.
But from what he has observed? First, asking her to fuck off would no longer be an option because she'll just be a detective and come up with some grandiose reason as to why she's not the bad guy and second, arguing with her would provide no merit than a pain in the ass. Still, there were parts of her personality that he personally didn't like so he prefers to be upfront about it.
"Your temper is not an issue. The issue is that you just don't listen when people tell you to fuck off and go home."
He doesn't care whether or not she likes his vulgar attitude but beating around the bush wasn't a game he wants to play.
"You want an explanation, Doc? Here's my offer to your question."
He looked at her straight in the eye, giving her an answer that she wanted all along - an explanation called "no".
Her issues with her temper was the least of his worries because if she got pissed just because she couldn't handle his words, then it'll be laughable to see who's the actual hero and the actual villain in this exchange of words.