This doesn't sound like the hybrid stance to me. It sounds like the pitcher came set with his feet aligned toward home, not opened up (left foot in the direction of the 45-foot point of the first base line) which is what I thought the hybrid stance entailed. But then he lifted his free foot, planted it behind him towards first, and then lifted it again to stride home.

The hybrid stance is (a) pivot foot "across" the rubber as if in the windup, AND (b) free foot in front of (a line through the front edge of) the rubber as if in the set.

It has nothing to do with the angle of the free foot. Maybe we're just describing the same thing in different ways.

I don't do FED baseball, so it may just be a misunderstanding on my part. I thought the hybrid referred to the "open" set stance that righties like to do with a runner at first.

That's legal. "Hybrid" means "part windup, part set" -- so the runner can't tell which is really being used.