Not a good direction to come from to support your argument.
The impact energy is related to the kinetic energy of the object (bike) at instant of impact.
The kinetic energy of an object is proportional to the square of the velocity.
25² = 625
32² = 1024
What you have demonstrated is that by increasing the maximum speed by 7km/hr, you have increased the impact energy by 64%.
eBikes are heavier than non-e bikes. A tough negotiator could use the above argument as a convincing reason to put a maximum speed limit on powered bikes. Be very careful!
And your point is? If my bike is limited to 25 and I ride it at 40 by pedaling it past 25? The impact at 32 or 40 is the same whether I have restricted the bike or not.
What I say though is if the speed limit was more realistic as in most countries outside Europe the need for derestriction will fall away. We've seen that first hand here locally.
I'm not in favour of derestriction and most of the time I ride my bike in Eco mode at the lowest setting and I am 63 going on 64.
I am however pointing out the obvious that if you make restrictions too ridiculous you create reasons why people start rebelling against it. The truth is that some of the derestriction that is done on bikes can not be picked up except by riding it or using sofisticated software, so if a regulator wants to test it they'll have to physically go and ride your bike or you can claim that you've ridden it at that speed under your own power. If your ride a US specced bike from any of the manufacturers in Europe it will support up to 32 kilometers and it has no derestriction software or dongles installed.
How do you police it? If you really want to you can impound all bikes that have been involved in hitting pedestrians and then test it. But here's the thing. How many pedestrians actually get hit?
So I'm going to leave you now with your silly 25 km/h speed limit which you are obviously happy with and defending with your life. And I'm going to look at how you're going to have the same news of eBikes and normal bikes hitting and killing pedestrians every time a person walks in front of a bike and gets injured or killed. The debate will rage on and then the authorities are going to start taking about banning bikes in city centres and so it will continue. Enforcing a speed limit to an unrealistic number to classify a certain type of bike while you're not limiting it's actual speed and still allowing normal bikes under human power to exceed that speed without any penalties is simply insane and beggars believe. You're telling me that speed is not the issue and go into long arguments about what an extra 7km/h does to the impact on a human being and then you tell me it's not about speed and that I'm missing the point. Huh? So why then your 7km/h argument?
You see a good defender will always trump the prosecutor who argued like that because it makes no sense.
So if you want to restrict speeds which is really what you want to do if you apply a speed limit on eBikes, you have to limit it on all bikes which means you have to fit speedometers as you can't expect a person to guess how fast he's going.
You're opening a can of worms here because what do you restrict next the pace at which people jog?
Start by providing dedicated cycling roads and stop arguing about a silly unrealistic speed limits that you can't control and that realistically is not statistically a real issue but an issue that's been escalated out of proportion.
In the UK a delivery biker has been found guilty of killing a pedestrian because he rode a bike without brakes at high speed. I agree with that verdict. He did something where he should have foreseen that his actions might have an impact with dire consequences.
Personally I believe mountain bikes belong on trails and that's where I ride mine except where I ride to a trail or between trails.
If a society needs to be policed so much that every actions is regulated it has become a really sad place and says very little of its moral fibre. What happened to people taking responsibility for their actions?
By all means, if a person rides recklessly and endangers other people, pull him off and sort him out but you have not convinced me that there is any realistic argument for a 25 km/h speed limit.