These are only meant to help for cases where the full tux is too detailed to display, see examples in the linked README. But the shape also works well for single fill cases, like in the keychain example. I wouldn't want these to be used when the full tux could be displayed in all its glory instead.
One issue I have is I do not know how to license these properly, I wouldn't want them to show up in a trademarked logo or anything, but I would still want them to be freely usable as tux icons anywhere. What do you think?
I have chosen the CC BY-SA 4.0 license, thank you for helping me!
Creative Commons is exactly the tool you need for licensing; they even have a "build-your-own" customized license tool. The tool will generate an icon, text, and a link to easily understandable legalese for your license.
CC is like GPL (but more flexible) for art, and it's an awesome service.