Indeed, he did change tactics w/r the bombing of Japan. My own take is that war is a dirty business and LeMay was brutally honest about the nature of it. I'd liken him to WT Sherman in outlook, rather than Grant.
"So, we get about a thousand ni-ju-kyus, see? We strip off everything they don't need - guns, excess fuel, superfluous crew, see? We replace all that deadweight with incendiaries and we roll 'em in low and slow, so big that Tojo can smell the exhaust. Let 'em suck on that one for a while. Think of it as a wall-to-wall carpet of jagged steel and white phosphorous, courtesy of USAF interior Decorating. "
Just channeling...