Well, no. For starters, you’re forgetting that gravity it’s probably the only force acting on a bike that’s linear with speed. And even it technically isn’t linear—just close enough to be a good approximation over human scales. But air resistance goes with the square of speed. i.e., to double your speed requires quadrupling the power.

More importantly though, there’s also a speed cap. EN15194 has a hard cap of 25 km/h. It can provide up to 250 W of assistance if you’re doing 24.9 km/h, but the motor must cut out entirely and be no help at 25.1 km/h. It also must be pedal assist, meaning it can only provide power while you are also providing power through your legs. The exception is up to 6 km/h it is allowed to assist with a button or throttle, sometimes called “walk mode”.

The NSW law is a 500 W cap at present, but the law specifically calls out that it must “progressively reduce as the bicycle’s speed increases beyond 6km/h”, in addition to cutting off at 25 km/h, and the pedal-assist requirement.