Yes, you're right, of course, the two concepts are different but not, I think, unrelated. One of the major arguments used to support the 'interviews are canon theory' is that because JKR is the author of the books, she must know and understand them best and who are we, who've only read them, to query her answers.

And yes, you don't have to hang out with the people you disagree with. But it doesn't make the discussions where you're realising you disagree and why any less frustrating!!