I also don't think it's true. In addition to writing code for the std.* Phobos library, I think Andrei has been using D for data processing stuff related to his recently finished dissertation. He would make comments from time to time about this or that not performing well enough in std.*, and then go fix it.
>> Walter Bright listens to Andrei (ok, a smart guy) but he doesn't write D programs
You stated twice that he doesn't write D programs. Well since you are mentioning Tango, it's unfair because he writes code for a _standard_library_. And he is writing a good code.