[PhantomGremlin]

I don't think this kind of decision was ever made public, was it?

Not that I'm aware of. I follow the misc, tech, and libressl mailing lists and there seems to be a lot of OpenBSD related stuff missing from there. I think the cabal uses other, more private, more informal, means of communication for a lot of their discussions and decisions.

selecting old versions of specific files

But did they really select an old version? Rather, perhaps they just declined to pull the changes that the OpenSSL people made.