You know, the first time you navigate somewhere (if you don't already have perfect directions) will probably be the longest route you'll ever take to get there

For Earth, the proof presented for NS is just our first attempt navigating from our previously known facts to the proof.

I expect we will be able to shorten it dramatically (most likely with human and AI insights), but I don't think we should read too much into the length. If you want a similar point of comparison, see the original proof (by humans) of Fermat's last theorem. It has been shortened significantly. This is normal.