To give some historical context: There was and is still a lot of
software
out there sloppily declaring itself as "public domain", which, in many
jurisdictions, is not even legally allowed. So Fedora has over the years
tried to approach those upstreams convincing them to adopt an all-permissive
license instead. And, there comes the point: Fedora has EXPLICITLY SUGGESTED
CC0 to those upstreams as a legally sound alternative to use!
This (last part) is correct. Fedora (and also I, personally) advocated for the adoption of
CC0 in the past (for me, this was sometime prior to the past ten years I think). I think
that ought to be borne in mind in considering how the change of policy is implemented.
So, e.g., CC-BY-SA is also not acceptable for software?
That is currently the case: CC-BY-SA is classified as "allowed-documentation"
and "allowed-content". I think in the past Fedora (like a number of other orgs
in FOSS, I think) discouraged its use for software, but this was not really because of the
"no patent licenses" clause, which has mostly been overlooked.
Richard