I've used MC to read SACD ISOs and that works. Though it's strange because renaming or moving the ISO can destroy all of your edits to the individual tracks. If I had more of these, I would figure out some other way to handle them.
I don't have any CD ISOs. I just tried to make one with my ripping tool of choice, XLD, and there's no option to do so. A little bit of research says that Disk Utility can do it, but some posts I've read say those ISOs aren't readable from a CDDA (Audio CD). I have not tried it yet.
I have ripped many hundreds of my CDs into individual FLAC files and MC works quite well with them. Are you just curious about this because it was an option? Or is there a specific goal you are trying to achieve?
My guess is that MC doesn't handle CD ISOs very well on the Mac, but that's just a guess since I don't have any to play with.
Brian.