By this description a throttle seems worse for ergonomics because it requires you to keep your hand in a single spot. Hand placement is an important part of balance and riding dynamics.

Ergonomically, my bike makes it very easy to operate both the throttle and brakes with my hands balanced on the handlebar. I’d hope that’s true for all bikes, since you don’t want braking to fuck up your ability to maintain balance. Bikes are designed such that you can use the handlebars and finger-accessible controls simultaneously,

Foot position and pedal rotation is ALSO an important part if balance and riding dynamics, especially when turning through intersections at 20 mph. Instead of managing gyroscopic forces and compensating my balance, the throttle means I can lock my feet in place, stand up, look around, get better visibility, and be in better control with better awareness in high-traffic areas. All of these things make me safer, and keeps me aware of e.g. pedestrians who this bill supposedly benefits.

I am not familiar with urban commuting, as I’ve never lived in an urban area, so I can’t comment on that specifically. I regularly cross busy 2-3 lane highways with 55 or 65 mph speed limits, with sometimes only a stop sign to help me do so. There are two big ones that I cross in each direction of my commute, or four per day. Depending on where I’m going and the weather, I take different crossings with different risk levels. In fact, 80% of my commute is along roads with 55+ mph speed limits; many of those roads include sections with steep, hilly terrain. Having a throttle to go from a standstill and quickly cross gaps in traffic, or to keep my speed up when fast-moving cars have low visibility in the hills, is a huge safety boon in my commute. It keeps me and those around me safer.