

Disk rot usually happens when air gets in contact with the reflective coating and oxidises it. With CD’s, it’s actually the top side you need to be worried about, as it’s right there under a thin lacquer coating. Any ding to that can expose the layer or just literally chip off a chunk of data.
At least on DVD’s it’s sandwiched inside the disk, so usually the only reason is a manufacturing error, and not really something the user can cause.
IANAL, but the way the federation by necessity copies your posts and information to every instance there is and to be able to do that it all needs to be under a licence that allows it to happen, those blurbs almost certainly are legally entirely meaningless. The only thing I can think of is claiming a non-commercial use violations, but that could put every instance that runs on donations under fire as well.