I had a Columbus semi hollow copy back in the 80s that bent like that and kept going out of tune... Felt very guilty about selling it, but I didn't hide that there was a problem. It had no centreblock and I suspected it was the body but had no real idea how to diagnose it. I'm not sure, actually, if I have many more ideas now without a lot of very technical measuring kit. Simon's idea of clamping the neck has a lot going for it... I wonder if you could clamp the body down to a solid surface and have a reference point/scale against the end of the headstock and see how much it bent against a standard load with or without the neck joint clamped.
If it was genuine scrap it would be a good thing to take apart and try and mend because you could learn so much, but seems as if its better than that.