To expand on this a bit, in many places a software project without a license means that all rights are reserved by the author and that nobody else has any legal right to use it in any way.

I'm not sure if unlicense/public domain would be a better default though. At the very least, that Github prompt should explicitly state with a warning what it means when you select "None" as the license. I think most people don't realize or know what it means for others who want to look at or use the project.

Wasn't it MIT or something permissive long time ago? I felt prevalence of "it's marked as ___ but actually proprietary" might have influenced that