This is a topic that I'm sure will ruffle some feathers but I will say living in the US that there is a level of noise where it's indeed possible to be heard. Some motorcycles are modified to be deafening loud to the extent that they will shake the windows in houses within a city block when they pass by. I find it kind of rude and attention seeking. If someone is so afraid of being on a motorcycle that the only way they are willing to do it is if it's so loud even the deaf know they are coming from a mile away maybe it's best for everyone that they trade it in for something they feel safer in. I am in love with the intoxicating sound of a supersport at high RPM though. When I hear them go by it makes me miss mine.

I don't think many motorcyclists have ever ridden an electric bike. So the survey is pretty worthless.
Do the same survey with riders who have already ridden an electric bike and the figures will be way higher.
I've had the chance to ride the Harley Livewire and it's a bomb. Only the high price (35k€) stops me from buying one. I admit it's really a one-up urban machine but that would suit many. It's only time before we see more electric 2 passenger bikes on the market with a reasonable range. So when and where could I ride my 1944 Harley WLA...

And how many that currently are not riding would start if decent electric bikes became available and affordable?

At my age, its a moot point. I dont even know if I'll still be in this world in nine years time. While in my youth, I expected to cover up to 800 miles in a day, those days are long gone. Partly due to traffic congestion, speed limits, and/or my personal strength and stamina. So I'll leave all such considerations to those who'll be affected by them, and good luck to them.

My '97 GSX-R 750 was my first new bike with a quiet factory exhaust, and I had lots of problems with people cutting me off and merging into my lane. About a month later I put on a slightly louder (not Harley loud) Yoshimura exhaust and it made a huge difference with people's awareness. I continue to put aftermarket cans on my bikes, and the thought of a silent bike is concerning because of clueless idiots in cars. And since I drive a car with the radio on too, I know you can hear bikes from inside them even if the bike isn't redlining at 110 dB. Maybe Romanian cars are just super insulated compared to others.

Back in 1964 at the Blackpool motorcycle show, the Lucas stand had two electrified trials bikes, a BSA C15T and a Greeves Scottish, with a small trials section on the actual stand and I had a ride on the BSA.
Crude by today's standards, power control was an on/off switch, but good fun.
That must make me one of the first electric motorcycle riders ever!
I still ride and own a 1950 Mk V Douglas 350cc, a 1957 Ariel Red Hunter VH 498cc and a 1957 BSA Clubman Gold Star 498cc.
There is no way an electric motorcycle will ever approach the appeal of any of those, especially the visceral feel and sound of the big Goldie as it comes on the cam and the inch and a half Amal GP carb starts to breathe around 4,500 RPM.
Yes, electric motorcycles may be fast, but they've got no soul!

Loud pipes save lives. No doubt about it at all.
When I ride my Ducati with loud pipes I generally get a buffer around me of at least 50m both in front and behind. This in Belgium, where otherwise I'd have car drivers constantly tailgating.

No one will miss them and their needlessly loud polluting machines that need constant care.
And so many new riders coming in as so fun, low cost, no motor to maintain the losers will be a rounding error.
I gave up riding ICEs long ago after getting tired of keeping the machines running, bad gas mileage and been driving EV trikes, subcars for 29 yrs now at under $1/day.

I expect there will be a market for some kind of speaker for mounting on an electric bike (or car/truck) so that a deafening roar can still be had. As for myself, I'm an advocate of Quiet, so I will be looking for laws to limit such racket.

I drive EVs and will eagerly replace my ‘19 Honda Rebel 500 with a reasonably priced electric motorcycle IF AND ONLY IF someone makes one that looks like a motorcycle. I despise the ducktail rear end of all existing e-bikes. If that’s the only choice, I’ll ride my Rebel until gasoline is no longer available.