"Entertaining" isn't a word I'd use to describe that overlong digression in an otherwise entertaining novel. I love Stephenson, but he sure could use a stern editor at times.
For what it's worth, there's a huge audience for Stephenson's work, so I'm perfectly fine with him digressing in his books - I always enjoy it on a first read-through, and most of them are enjoyable during a re-read, too. No need to try to take those away to satisfy a slightly larger audience.