This is a specific case that (maybe) proves the general claim that P != NP.

Proving an inequality is "easy", because only requires a single counterexample: if there is one problem in NP that is not in P (I.e. an NP problem not solvable in polynomial time), then NP can't possible equal P.

Fukuyama is proposing that CLIQUE is such a counter-example.

(Proving the inequality doesn't actually require the special property of NP-completeness which others are talking about; that is only useable in a proof P = NP.)