One thing to keep in mind is that version freezing is only for application builders, that information probably needs to be included in information that educates about PVP vs. reproducible build.
Linking to the reddit discussion, a comment that had the most upvotes was completely confused on reproducible builds, here is the commenter's explanation of what a reproducible build is:
You're probably right; Simply stated, I considered "reproducible build" to mean that if there was a package on Hackage that I could cabal install foobar with a given GHC version at some point in time, I would be able to do that for each later point in time (e.g. 1 year later) using the very same GHC version (at least). Isn't that was the PVP was created to accomplish in the first place?