There's no control over what comes up as alternatives. If I could turn the bloody alternatives off, I would. There's a reason the Snowfeather is the 3rd pet; it's the fastest falcosaur and is guaranteed to beat Old Blue's speed.
I looked into it and you were correct, the original string was for the Sharptalon from one of my earlier attempt. I've changed it but for some reason the code is different? I don't know why but both scripts actually work.
Predatory Strike will not kill Old Blue if Falcosaur Swarm! has not hit him beforehand.
My Direbeak Hatchling died before it had a chance to hit him with it and Snowfeather Hatchling had to use it once before Predatory Strike.