Passenger seat removal in Prius Prime ?

I don’t know of anything in Toyota’s publications that suggests that a disconnected or malfunctioning airbag or seat bent pretensioner would cause the others not to be deployed, if needed. The Electrical Wiring Diagram (more info) shows that each airbag assembly has its own connection to the airbag sensor assembly, the ECU for the supplemental restraint system (SRS).

The risk, instead, is that with the seat removed, the SRS warning light would always be on, so you wouldn’t know if there were a problem elsewhere in the system. I’m not sure there is a good workaround for this; as in older models, you could connect a 2.1 Ω resistor in place of the missing airbag squib, but on fourth-generation Prius and Prius Prime cars, the front passenger seat also contains the occupant detection ECU. This ECU communicates with the airbag sensor assembly over a CAN bus, and its absence would be noticed.

I wrote this in an earlier thread, but it bears repeating:

The Repair Manual (more info) has a several pages of important warnings about how to avoid personal injury or property damage when working on the supplemental restraint system (SRS). The most important precaution is to disconnect the negative (–) terminal of the auxiliary (12 volt) battery and then wait at least 90 seconds before doing any work on the SRS wiring or parts. Never try to measure the resistance of an airbag or seat belt pretensioner squib, since the small current from a meter might be enough to fire the squib. The Repair Manual also explains how to lock and unlock the airbag connectors.