You are not owed a license. You are not owed neither software nor hardware. If you don't like it, re-create all the work, but don't plagiarize, and release it under whatever open source software you want.

Half the time people with new projects just forget to choose one. He could put up a completely non commercial license if he wanted. It doesn't even have a copyright notice right now, making simply overlooking that so far the most plausible explanation.

That's correct; it's far from finished - I just chucked it up on Github to show it to some interested folks and get some review on the design. Didn't expect it to actually get attention.

The plan is that once it's working to my satisfaction, I'll do a small production run and release the designs under some kind of open hardware license. I'm not particularly interested in making money off it beyond covering my costs.

Your initial statement kinda reminds me of those hobby game development projects that get stuck at choosing an engine/tooling and never build an actual game.