The proposal has two separate crew access airlocks with their own lifts, two separate cargo cranes that can be used in an emergency, and presumably some rope on board that the crew remaining in the vehicle can jury-rig to drag the EVA team up if necessary.

The sheer scale of Starship is stupefying. If it ever gets there, it will in one go transport tens of times the payload of every previous lunar mission put together. The scale of what it can do will allow it to be quite a bit less efficient about things than everything else has to be, and so it can spend some mass on redundancy of important systems.