Problem with that is that programming languages are not just about ASTs, they also have different semantics. A "class" in C++ is not like "class" in Java. Nor is it very easy to translate between a garbage-collected language and a one with manual memory management.
One could think that such an "AST in database" solution should have one agreed-upon semantics common to all its textual representations, but at this point you may as well serialize your AST into s-expressions and suddenly you're writing in Lisp.
Yeah, my recollections are from a talk I attended 17 years ago, so details may be a little off. It was the first time that I ever saw refactoring demoed. I have no idea what happened to it in the longer term, I know that Simonyi left Microsoft and started a company just to pursue intentional programming.
FWIW I do remember that the name comes from the ideas that the most important thing that a developer does is express intent. I've found that to be a powerful way of thinking over the years.
Code stored as AST in a database, text representation in a specific language is just one of many possible views