What Charlie is saying is simply that there can be sounds where the pitch is harder to discern or starts to approach white noise, in which case our brains can't process the pitch the same way we can with other instruments due to its acoustic properties. It doesn't mean there's no pitch. It's like saying that just because we can't see ultra-violet it doesn't exist.
So long as something is vibrating, it'll have a pitch. Regardless if we can or not hear it, discern it, or anything.
Hence calling an instrument non-pitched is nonsense. Indeterminate is a better word for it, as it's what the actual effect is.