Scary stuff! Touch would I’ve never experienced a speed wobble on any bike. It seems to me like an unlucky combination of mass and frequency leading to an undamped resonant oscillation. If I ever experienced a speed wobble like this I would never trust that bike again. But a different rider on the same bike with a slightly different mass (lighter or heavier) might never have an issue as it would change the resonant frequency.
I agree with the poster above who mentioned that wider, lower pressure tyres are likely to help damp out this kind of resonance. They certainly feel more stable to me at high speed. My current road bike (Giant Defy) on 32c tyres at 65-70 psi is rock solid on descents. But I do hope I don’t think about this thread next time I’m bombing down a hill!