Not legal. This group does not concern themselves with copyright law.

Currently it says they have released metadata and album art. Is archiving and sharing the textual track metadata alone (no images, no audio) legal in the US, or Europe? By what basis is it legal or illegal?

Adherence to the legal framework is a function of your risk appetite.

Very, if we delete copyright like we're supposed to.

Not legal

Completely illegal.

It's not. It's awful people justifying awful behaviour. And it's why we can't have nice things. There are always assholes ready to exploit others.