Yeah, "canon" tends to be more of a fannish hobgoblin than anything else. As I've mentioned before, back when I editing the FARSCAPE novels, I was in touch with the nice folks at Henson every other day or so, and during that whole time, I don't think the topic of "canon" ever came up. It just wasn't an issue that had anything to do with actually producing the books and getting them out on time and on budget. Likewise, the topic of "canonicity" appears in no book contract or licensing agreement that I have ever laid eyes on. It's an abstract issue, not a practical one.
It wasn't until I started plugging the books at conventions that (invariably) I started getting the question "But are the books canon?"
The honest answer: they are until they aren't.