VERY dangerous to go over even 75 mph on, say, the Deegan without these stabilizers/fairings.

Rubbish. Lots of fast, safe bikes have neither. Mine is rev limited to
a top speed of 160 IIRC. You're doing the same thing Wieber does,
taking old limited knowledge and using it to make **** up. I think
Wieber had an old 600cc boxer. Those were something like 45hp. I'm
beginning to wonder if your experience is about the same.

Maybe these guys lack experience too?

Oscillation is a desireable action... if you're on a swing at the park. It's a nasty action at 75mph on a motorcycle, and shag nasty at 160. We spoke with Jason DiSalvo's 2009 AMA Crew Chief, Michael Tjon Sien Kie, about "head shake" and the steering stabilizers
https://www.youtube.com/watch?v=RP-UfUrymY4
Funny, they mentioned the same 75 mph I did.

There is a one word explanation: resonance. Look it up in wiki.
Different road conditions will set up different resonances in different bikes.

What's funny, oblivious, is how authoritative you are, ALL the time.
And did you ever bother to think, Gee, just why do people use these? They're even used on bicycles.

But, Oblivious, feel free not to use one, and please please go as fast as you can.