Yes, this is really the main thing. If you teach a kid to say "5 times 5 equals 25", they'll be correct regardless of whether they understand the words,

The same goes for any words anybody says ever.

Now, if someone tends to say a lot of stupid things, then that does mean the probability of them saying something smart might be relatively low. So for instance, in the case of this one author, I don't really feel compelled to read her book, because I think the probability of me finding something interesting in it is fairly low.

But just because she didn't have a good interview (or a particularly insightful follow-up on Twitter, for that matter), doesn't mean the main idea she's defending has no merit on its own.