Hum, What nobody seems to want to ask is why you would even need to use the neutral in a 120/240 volt single phase (split phase) system to make a rotary phase converter using a 240 volt three phase motor. Maybe if you have some 120 volt control voltages on the timers and contactors but all you would have to do is get components with 240 volt control voltages. So apparently this design is not very robust. There are easier ways to make a rotary phase converter from a three phase motor, some contactors, some run capacitors, and some timers and or potential relays.

And where do they bond the "ground" to the "neutral" on the secondary side of a transformer bank at the power pole? The only place they normally bond a "grounding electrode conductor" to the "neutral" is at the service entrance.