It's important to make clear that this theory was reported by Haldeman long after his alleged conversation with Nixon. If Nixon did say this, then in terms of his obsession with victory in Vietnam, the short answer is no. North Vietnamese documents suggest that officials had a strong grasp of the situation in the U.S. and the pressures Nixon faced to end the war. I'd be the first, however, to say that the use of such psychological ploys in both military and diplomatic circles could be and have been of great use. For more info, see Jeffrey Kimball's work. I also believe Richard Immerman has an article on this topic.