Regardless if it’s a unibody or a welded chassis parts of it would be designed to give under stress and parts of it would be designed to hold to protect the driver.

In a bad accident with any BEV i would be far more worried about the battery being compromised than the chassis tho.

The point that's being made is-- if there's a certain amount of energy being dissipated in a collision, it's better for things to crumple so that the energy is dissipated over a long time period and the peak accelerations (which damage occupants) are less.

A hypothetical perfectly rigid car that stops instantly in a collision instead of deforming is not safer for the occupants, because suddenly they will be going 40MPH inside a not-moving car.

Absorbs? What does it do with that energy, then? Radiate it? AFAIK it's just stiffer so it will effectively transmit the energy along to the next part in the chain. Eventually, that'll be a human.