[I'd put this in an open thread, but those don’t seem to happen these days, and while this is a quote it isn't a Rationality Quote.]
You know, one of the really weird things about us human beings […] is that we have somehow created for ourselves languages that are just a bit too flexible and expressive for our brains to handle. We have managed to build languages in which arbitrarily deep nesting of negation and quantification is possible, when we ourselves have major difficulties handling the semantics of anything beyond about depth 1 or 2. That is so weird. But that's how we are: semantic over-achievers, trying to use languages that are quite a bit beyond our intellectual powers.
— Geoffrey K. Pullum, Language Log, “Never fails: semantic over-achievers”, December 1, 2011
This seems like it might lead to something interesting to say about the design of minds and the usefulness of generalization/abstraction, or perhaps just a good sound bite.
I read the point as saying that language is capable of greater depth than humans. Das nicht nichtet is a coherent statement despite the objection of the logical positivists, but it is really deep.
As an aside, I'm not persuaded that metaphysicians are saying anything useful. But the objection that their statements were incoherent is a stronger objection.
The interpretation of some of Heidegger's statements as incoherent isn't just something his enemies came up with; it is supported by other statements of Heidegger's (as Carnap notes in his criticism of Heidegger). I really am curious as to what coherent statement you think you can find in "the nothing itself nots."