Are we looking at the same pictures? The entire rear end of the vehicle is compromised in the pictures I'm looking at.
The issue is not whether something can be driven. A car can be cut in half and welded back together and track straight down the street. That doesn't mean it's a vehicle I'd put my family in. This car can't sustain another hit like it just took. Everything that is crumpled in the picture was a one-time use of the car to absorb an incredible amount of energy during the accident. The next accident will transfer as much, or more, energy back into the vehicle and all of those areas will never be as strong as they were the first time around. That means the next hit will transfer more of that energy deeper into the vehicle. It makes it worse that it's the rear quarter, which is more structural than the front panels. Everyone here is driving a unibody so we can all go look at the vehicles in our driveways to compare the front clip vs. the rear to get a sense of how much either can sustain and still maintain structural integrity.
That's only my opinion, of course, but I just don't see any reason to save this particular vehicle. It's not rare and it's not worth anything special. I wouldn't save a thousand or two dollars and still feel comfortable with my kids in the back. Not when the drivetrain and cosmetics can be sold off for much more than the car is "worth" at this poin and he's already getting a generous offer from the insurance adjuster (who was able to evaluate the damage a lot better than our "analysis" based on a couple pictures). I haven't checked the raw scrap prices lately, but about ten years ago I got ~$300 for a wrecked car that I had stripped to the bone so it wouldn't surprise me if $600 was just raw scrap value for that car, which was one of the flags that the adjuster was seeing structural damage.