Without descending to the status of low farce, deterrence theory and nuclear strategy only works if you don't declare your hand. There's no way of dressing that up as anything other than being a statement of fact.
There is no opinion in the mechanics of how deterrence theory works; the key fact is the inability to know whether your opponent will use it or not and that's what CDS stated. Misinterpretation doesn't turn that fact into an opinion.
Whether you think CDS was correct to discuss the mechanics of deterrence theory in public is your opinion, but it doesn't alter the fact that is what he said.