Actually, the "canonicity" of off-screen events is an open and shut case. The producers can say whatever they like; they don't own the show and ultimately that call belongs to the people who do - and then, only in the sense that they approve or don't approve scripts, etc. because the studio doesn't actually care whether something's "canon" per se. They care only about whether they believe something enhances or diminishes the value of their property. Canon is a fan obsession, nothing more or less. This is why it's been violated thousands of times on-screen.