They also have: https://sourcefirst.com

Thanks! That's a much better explanation.

This is very, very confused. It comes off as dishonest, but isn't; it's just the case that the developer doesn't get it. It seems well-meaning, but badly done.

Developer: I am, in all honesty, glad for the experimentation. However, you should understand that critical issues include the ability to remix. I cannot use your code in my project. Ergo, it is not open, free, libre, or similar.

You're better off underselling and overdelivering. The term should also convey what this does. I like "source-auditable" or similar. "Source-first" says nothing.

You should also think about longevity. How do I know the license won't change next week?

I think that the stuff they are putting out on sourcefirst.com is more of a formal treatment of their licensing terms and how they work. The stuff there is versioned iterations of something. They also bought the trademark for the term. They clearly want to lock it in as a set of standards.