Yeah, I'd count the author's bike as being pretty close to being a moped. Except that it might get regulated as an e-bike, and it is possible to use it as a normal heavy bicycle if he wants or if the motor fails.

The law in many US states and most European countries views the machine in this article as a moped or motorcycle. It is throttle-operated, instead of being proportional to pedal torque, and it has no speed limiter. If it was limited to 20MPH, it could be a "class 2" or "type 2" e-bike in many jurisdictions. If it was pedal-operated and limited to 28 MPH, it could be a "class 3" e-bike. But as built, it's a moped. You need a license, registration, insurance, and a helmet to operate it.

Maybe the author lives in a state where this is fine? Not all places have the same laws.

The author made a cool thing and did everyone the service of documenting the process. Why is everyone so quick to crap on his project?

If you can pedal it, it's a bicycle.

I see a lot of deliverymen around here with beefy e-bikes who never pedal. The question of whether you can pedal seems academic if you never do. These e-bikes I'm talking about are functionally identical to electric mopeds (same power and speed capabilities); they just have pedals that go unused instead of a footrest.

The law recognizes this too, which is why e-bikes are primarily regulated by power output or top speed.

Moped = motor + pedal