My own reading of the situation on the developer's GitHub is unfortunately that the review by Mozilla is indeed completely inaccurate in every way. No way to even read it as a "Each side has their own story" type of thing since they reproduce Mozilla's emails verbatim. They seem just materially incorrect. The source files referenced by the emails are visible on the same GitHub account, along with their complete histories showing no changes at all - the issues referenced don't and never did exist.
The only redeeming thing I can find is that the dev (ambiguously) seems to have never replied to the email from Mozilla about the issues, and so Mozilla was never made aware that there was an issue with the review that needed fixing. They seem to have done this because they perceived the process as hostile and not worth engaging with, which... fair, I guess.