I don’t know if that is true or not, but if so, I guess it is a stirring endorsement of the idea of being a nice liberal democracy that people want to move to.
There was single significant defection before the introduction of the "teen" fighters, codenamed HAVE DOUGHNUT, and even it was not actually Soviet (an Iraqi pilot defected to Israel). All the other defections (which there were several) happened using old/non-fighter aircraft (iirc there were several MiG-15/17/19 which were essentially Korean War era designs), or happened after the teens were designed.
He might be talking about Belenko's defection with a MIG-25 to Hokkaido in the early 1970s. Though neither aircraft is really related to the other except in very basic visual sensibilities (twin engine, twin tail).
And F-15 had its first flight four years before the MiG-25 defection. So unless they had time machine at hand its unlikely that it had major influence on F-15 design
My impression is the Westerners’ best guess about the Mig-25 contributed significantly to the design of the F-15 and helped to make it what it is. Getting their hands on it was a relief, or even a let down.
The alternative scenario, where the Mig-25 really was generations ahead, plays out in the movie Firefox from 1982 where the US is so far behind they have to steal a Soviet Mig-31 superplane. Good for laugh today, but once upon a time…
The rumor I heard is Soviet intelligence infiltrated American industry and stole what they thought were plans for America’s next generation air superiority fighter. What they’d obtained were the plans for Plymouth’s Roadrunner Superbird, thus the Mig-25’s uncanny resemblance. Proof: https://robbreport.com/motors/cars/1970-plymouth-superbird-a...
The, probably slightly played up, version I heard is that the US saw the propaganda version of the Mig-25, and so built the F-15 to counter that imaginary beast.
