I am assuming the switch is there simply so there is not live power to contact when the robot is not at the charging station. Depending on the voltage it is a safety feature that would prevent a human or animal from touching a live positive and negative terminal. It is hard to verify without seeing the circuit or schematic for sure. My best guess is that if you bypass the switch it would simply allow the contact to be live all the time.
It is very unlikely that this is more than a “dumb” switch that says the robot is here. There is would be a current sensor somewhere on the robot that would tell when the battery is charged.
I don’t think this would be the case. If it was it would be like someone was putting it on the charger and taking off. Like flipping the light switch. It would not say that it was fully charged.
I am not sure about this model however, the Roombas use separate circuits for the charging station vs the direct plugin with separate current sensors.