would you listen to the docs or random-internet-person.
We don't expect person writing a Ruby binding for sqlite to know the theory behind database indexes and who are the acknowledged experts in that field. Yet we seem to expect that from a person writing binding for RNGs.
We don't? More to the point, do we expect them to close a bug related to those things without educating themselves on the subject enough to make a rational decision on it?
It's not the best solution, but if I ignored everything I know about this issue, I think it's a reasonable maintainer's approach.
A startup founder often wants to work themselves out of a job to do more useful things, most will do all they can to insulate themselves into indispensability (a lot of technical people are super insecure, I'm proly one of them, and a lot of corporate gigs are cut-throat fiefdoms).
It's reasonable to make this mistake initially sure. But when it's pointed out to you that the documentation is flat out wrong for reasons outside your and others control and you are pointed at articles and research by the experts in this field and you elect to ignore them then the security flaws that will result are very much on you just as much as they are on the linux man page maintainer.
As for "Also, why are the Ruby devs so dead set on the manual page?" - because it makes sense. If I didn't know much about random number generation, I'd rely on manuals and most widely adopted software. That means: urandom says it's not good for that usage, while openssl is used by almost every system. If you used a dependency that documents it does X and someone tells you that actually it does Y, but you have no ability to prove it either way, would you listen to the docs or random-internet-person.