Just broke out my Aqualung Blu-ray disc and spot-checked quite a few songs, across multiple audio options, and it seems to still be fully functional, so I guess I'm lucky, so far anyway. I made an MKV backup of the disc when this issue first came to my attention, as detailed earlier in this thread, so it won't be the end of the world if my disc eventually rots, but I sure hope it doesn't anyway.
Right now I'm playing through and enjoying the quad mix, despite my usual preference for Wilson mix. I suppose I've been a bit of a 5.1 snob in the past, assuming that most quad mixes can't be as good as 5.1 or Atmos mixes done with newer technology and expertise. But, perhaps ironically, Apple Music streaming, which has exposed me to a lot of cool 70s quad mixes, as well as a lot of mediocre Atmos mixes, has given me a new appreciation for quad. That, and the Dutton Vocalion quad SACDs I've bought, which are almost all great. Not to mention, quad vinyl & tape conversions
shared digitally (oops, did I just mention that?). This old dog is still learning, even if I can't always remember what it was a week later!