I thought she would be, but apparently classicist and historian have less overlap than I'd have assumed. I don't know how else to explain this one, I was shocked when I read that line.

r/askhistorians, which as far as I know is reliable, does not seem to dispute that they at least existed. https://www.reddit.com/r/AskHistorians/comments/1mwbdpd/why_...

Edit: Charitably, it could be awkward phrasing - not that the sea peoples didn't exist, but that the whole hypothesis around them is believed to be off.