About the 1-inch shield not being able to completely disintegrate a 1-foot diameter rock:

What I get from this is that the rock has to be smaller than the shield thickness... what if we reverse the impact perspective, with a twist....

I am a 1-foot rock at rest in space. A spacecraft comes barrelling toward me at 1500 km/sec, its front end apparently fitted with a Whipple Shield. I say to myself "Ha! That thin plating will not destroy me, for the part that will hit me is smaller in depth than I !!! Ha ha ha ha!!!"

An instant before the spacecraft hits I see that its surface is riddled with 1.5 foot depleted-uranium spikes. I now realize that the spacecraft will penetrate *me* rather than the other way around!

Would not the rock now disintegrate throughout its entire depth and volume?