As I understand it, the decoding of encrypted DVD and BD discs is external to MC. On windows it uses windows specific tools to do these decodes. I suspect those tools will never be ported to MC for Mac because they are not JRiver products; they are from someone else.
I'm not sure how you would support ISO DVD or BD under OS X. You can always rip them from the ISO files to MKVs with MakeMKV, which preserves 100% of the quality of the audio and video. Just no menus. Which is better in my opinion. Menus are a pain when you just want to watch a movie. Just MHO.
Brian.