First of all, get the terminology right. The RYF certification is for hardware that runs on 100% free software, and the Librem 13/14/15/Mini will never get this certification because they contain microcode, FSP and 9% of the ME, which is proprietary. Purism is only trying to get RYF certification for the Librem 5 phone, not for its PCs. You may be right that the FSF won’t grant RYF certification for products that have official instructions on how to install proprietary software, but the RYF criteria page doesn’t explicitly say that.
However, we are not talking about the Librem 5 here (since its RS9116 doesn’t require proprietary firmware in the Linux file system to use Bluetooth).
The FSF officially endorses distributions that contain 100% free software, and PureOS has received that endorsement. It is an open question whether the FSF would have endorsed PureOS, if Purism had instructions on its web site how to install proprietary firmware. When I have asked the FSF questions like this in the past that are matters of interpretation, I haven’t received a reply.
Personally, I think that Purism should set up a general community wiki for all its devices (like it has for the Librem 5), where the community is encouraged to post “unofficial” documentation. I have answered questions on how to deal with WiFi/Bluetooth on Librem devices at least 3 different times, and this kind of information should be centralized somewhere, so we don’t have to keep repeating ourselves.