Yes, the Jip steering shaft will collapse. I wouldn't have done it to my truck if it didn't and probably even more so than the Astro shaft. If you see the 2 while plastic filled dots in the shaft, those are designed to break loose and let the shaft slide into itself. On my Jip shaft upgrade, I simply put RTV silicone around the top 2-3 inches of the inner shaft just to work as a cushion between the 2 shafts, but yet be able to collapse and it's got about 4 inches of room to do so, not to mention the U Joints in the shaft break away quite easy. I know becasue I pryed a little bit on one of the Jip shafts when removing it from the donor Jip at the salvage yard, and the U joint section broke. I'm only talking maybe 25-30 lbs of force and broke, so I know in a collision that can also break away at either the gear box end or the column end and fall away from the steering colunm in a serious frontal collision.
A good old hs buddy of mine's brother was killed in a survivable accident in a Dodge Power Wagon 4x4, probably a mid to late 70's truck, when the steering wheel broke away in his hands from him holding on so tight and pushing, then the steering column came into the cab and up and stabbed him the adams apple and killed him instantly on impact. I seen the truck, yes it was a hard hit, but with a seat belt on, he should have survived. The part of the steering wheel that was left was about a foot from the cab roof, and about a foot from the back glass that was also broke out from the back of his head hitting it. I firmly believe he'd have survived if the steering column would have collapsed.