> Again, I cite #25003: he implicitly ruled there that it's not permissible for os.urandom() to block on Solaris, so I think he agrees with me.

To be clear, that's an entirely different kind of blocking. That made os.urandom on Solaris behave similarly to /dev/random, where it would randomly block for all users of that API regularly. I would have made the same ruling, this blocking is not that blocking.