Unfortunately, aside from the situation pointed out by Bart in that thread (that some laptop bags are just too cluttered to discern all the scary things they hold), there really is no good answer for why my expensive computer cannot pass thru the x-ray machine in its protective padded case. My laptop bag does not contain all the sundry scary things that necessitate it being unprotected as it gets its radiation, but that's not how the brain-trust at the TSA works.