...This doesn't mean that some of the explanations offered in the novels wouldn't be sensible ones. Bringing them up is a good thing to do, then - they are one possible application of common sense, and a worthy competition and addition to the arguments being juggled here.
On the other hand, some are clearly less sensible than others, and some may even contradict what was seen on screen, which is a big no-no. Bringing up those should only be done to demonstrate things like "this
certainly doesn't work" or "see, the book is much better drama than the movie ever was, I wish things had gone this way, but alas..." and so forth.
Neither type of referring to the noncanon works is irrelevant to the overall argument. Only if one claims that the written word should be considered over and against
canon material and common sense is one getting lined up for a gang-smacking with boiled broccoli.