Yes, I understand all that. I don't share your intuition that it's gravity over a man-sized drop is obviously too weak to cause a large explosion. You haven't made an order of magnitude estimate to back it up.
My point is that there are many orders of magnitude difference between the relevant parameters of plutonium vs. uranium, so the fact that dropping plutonium cores against each other is insufficient to produce a large explosions tells us essentially nothing about that possibility for uranium.
My point is that there are many orders of magnitude difference between the relevant parameters of plutonium vs. uranium, so the fact that dropping plutonium cores against each other is insufficient to produce a large explosions tells us essentially nothing about that possibility for uranium.