There's a diagram if you look around. Sure the narrowest portion is narrow, but you need to bend your body because this narrow portion is at a curve.
A solid metal cylinder that can't bend had no chance at all to begin with. If a human cant go through without bending their body how can a cylinder containing a flat standing human get through? An engineer designing for this situation knows to optimise for the camera instead of the cave.
You know, I actually had been wondering about the length myself for a while, but I hadn't seen any comments or quantifiable information on that one way or the other. I was wondering how much they had considered that even in a narrow hole they might need extra room of more than twice the length of the tube afterward to make sure it goes through, if the passage doesn't go straight. The bendability per se I admittedly didn't explicitly think about, though (though it kinda factors into the size). Every diagram I've seen so far has been grossly not-to-scale for something this small, and every objection I've seen thus far has been about the diameter, not the length or the shape. If you have any information on the shape (besides the diameter) it'd be awesome if you could link it here. (Unfortunately I have to go offline so I don't have the chance to Google further right now.) Thanks for the reply!
A solid metal cylinder that can't bend had no chance at all to begin with. If a human cant go through without bending their body how can a cylinder containing a flat standing human get through? An engineer designing for this situation knows to optimise for the camera instead of the cave.