You will not get specific legal answers to your questions surrounding
this beyond what has already been said in public. There are only a
handful of lawyers on this list and they cannot give you what could be
construed as legal advice.
In the past Fedora has been willing to explain why MP3 decoders are NOT acceptable in Fedora. I have a really hard time believing that an explanation as to why that is no longer true cannot be provided, possibly with a suitable disclaimer. I'm not asking for a blanket statement that MP3 decoders are now completely unencumbered and that someone can do whatever the hell they want with them. I'm only asking what changed.