5 days? It’s been a lot more than 5 days of the silent treatment on this issue. See this thread: Nvidia SHIELD/Android app SSA/ASS format anime subtitles + transcoding problems
The closest I’ve seen Plex have to an statement on this is that when Exoplayer got support Plex could add support. Support has been added but no more response from Plex. However based on this reply Nvidia SHIELD/Android app SSA/ASS format anime subtitles + transcoding problems
It seems to me that Plex is possibly modifying the player in such a way that just upgrading the core player is not possible without big code changes to the player again. To me that seems like a poor choice, but what do I know. Plex never really talk about why they do what they do and why they make the choices they do on the forums.