I hate posts like this. Either tell him he's wrong, or tell him he's right but almost wrong. And then post your proof. But don't start the "I'm a bigger aircraft nerd than you" fight.
Hard-fact turn performance data for the F-15 is a little sparse to the public, especialy on the current stock in service. Taking into consideration we don't know the exact cessna model in question here but will assume it's one of the more common varieties with at least half a tank of gas. We also don't know the ordnance and fuel loadouts of the F-15s when directed to the intercept, but given they were cleared to break any window necessary between portland and seattle to get there ASAP they probabley could of dropped any extra weight and tanks along the way that they deemed necessary for speed and performance.
Assuming this cessna was not some high-performance-light-weight-supercharged model and just your typical tail dragger putting along with a healthy reserve of fuel and a picnic basket in the back seat, and assuming the intercepting F-15s were somewhere between the minimum and 50% maximum gross weight, the cessna is way outa his league on this one.
