An oversight in editing, yes. The pack is free now. I made it available to everyone due to a severe lack of interest on the GameDev community's part. Until I made it free and posted it on Reddit. Haha.
That is the downside of globalizing the amateur art world. The people who create for the joy of creating and/or getting attention turn it into a buyer’s marker within a generation or two.
Anyway, thanks for that. Now that everything is nice and clear, it being under CC-BY certainly means it’s suitable for my list of libre-licensed assets.
Here’s hoping it’ll add a donation or two to what you receive. (I certainly plan to donate something to each set of assets I use when I get back to working on my platformer project… given that the public domain tileset that inspired it isn’t set up to accept donations, I’m planning to CC0 the extension to it that I’ve drawn once the platformer comes out. I think I’ve at least doubled the number of available tiles.)