(please don't top-post. Surely you've been around this community long enough to know that)
My understanding was that unless activated by admin these changes
would change nothing.
That is assuming you can do this with changing just a couple of lines of code. Which you will not be able to do. The risk of back patching something like that even if off by default is *way* too large.
And they would be (borderline :) ) security fixes
No, they would not. Not anymore than adding a new authentication method for example could be considered a security fix.
And the versioning policy link actually does not say anything about
not adding features to older versions (I know this is the policy, just
pointing out the info in not on that page).
Yes it does:
The PostgreSQL Global Development Group releases a new major version containing new features about once a year. Each major version receives bug fixes and, if need be, security fixes that are released at least once every three months in what we call a "minor release."
And slightly further down:
While upgrading will always contain some level of risk, PostgreSQL minor releases fix only frequently-encountered bugs, security issues, and data corruption problems to reduce the risk associated with upgrading.
So unless you claim this is a frequently encountered bug (it's not -- it's acting exactly has intentional), security issue (same) or data corruption (unrelated), it should not go in a minor version. It's very clear.