I really doubt this. The amount of effort and acting that would need to go into being able to script in advance the sort of mistakes you make when programming would be astronomic. You would have to never make a typo when you weren't supposed to, always make a typo when you are, somehow deal with the fact that when you get stuck you need to be able to respond to audience feedback, and so on and so forth. (Oh, and interactive 3d programs not just text to a terminal).
That's a lot harder than making a programming language.
> Why doesn't he release it, then?
Because he doesn't think public feedback would be helpful at this time. Because he wants to release software that he can take pride in instead of a alpha level programming language. Because that's what he is used to from game development. Because he feels like it. Etc. Why does it matter? You aren't entitled to it.