Defending the view that Liar sentences are meaningless is a bold move, I think, though given my general misgivings about meaninglessness I have my doubts. But the way in which he builds a more general explanation and motivation for the meaninglessness of the Liar is clever. I do have a particular puzzlement concerning the purported use of disquotationalism:
What about sentences such as “It is perfectly obvious that this sentence is false”?
My initial intuition is that I can figure out the truth-vlue of this sentence without too much trouble. It might initially appear paradoxical, but as soon as you realize that there is nothing obvious about it, you realize that it is false.
Other sentences in the same genre are “It has been shown empirically that this sentence is false”, “it has not been conclusively proven whether this sentence is true or false, neither or both”, etc. And “It is not clear whether “this sentence is false” is true, false, neither, or both” seems a decent, and true, summary of the debate.
So, if I have understood correctly, his disquotationalist view implies that these sentences are meaningless. But to me, not only do they seem meaningful, but I believe I can judge their truth-values pretty easily.
(There may be some obvious point I am missing here, though, since “It has been shown empirically that colorless green ideas sleep furiously” seems equally meaningful and false as well….)