I love all the keyboard warriors who expect Lombard to be able to alter his punching instincts at the drop of a hat. That shit is hard-wired into his muscles and it was far from egregious. It was late, but just barely. DC had already commented several times how countering kicks with punches is part of Lombard's game. And when I rewatched it, paused it and slowed it down the first punch was landing as the bell started to ring, and the second punch was being thrown as the bell was still sounding and just as the ref yelled "time".
I don't think this was anyone's fault. The ref was calling time as the bell was still sounding, and Lombard was instinctually counter-punching as the kick landed and while the bell was still ringing. It's crazy to me that 1 second is the difference between a KO win and DQ loss. I think a NC would have been more fair, but it's an interesting gray area in the rules.