I mean, that's very easy to prove correct, since it's happened recently.

We hit 40% oil-fired generation on Christmas Eve this year, and prices spiked to over $2,000/MWh around that time.

Bloomberg article (archive link since paywall): https://archive.is/LnFvP

You could also just go straight to the source: https://www.iso-ne.com/isoexpress/. "Resource Mix Graph" and then pick 12/24/22 and look at it. At peak, we were generating 6.5GW from oil that day.