All I can say is that I wasn't aware of this discussion, or it blurred into the other discussions and didn't seem to need any attention from me. 
Once I was pinged on the pull request (and I'm *trying* to be better at checking GitHub notifications, though CPython is still the repo that makes it very hard), I took a look.

I definitely don't want to say that I must be consulted on every sysconfig/site/getpath change (because I don't want to be!), but I hesitate to say that this was the wrong way for it to be caught. It's only "too late" after a release has included it, and up until then it's fine.

So I guess it can be avoided in the future by checking the surrounding code and seeing how it's used? In this case, the schemes are all approximately static (for a given version of Python), and the *selection* of a scheme is based on the platform. The proposed venv scheme itself is based on the platform, while selection is static. That stands out to me as a difference.