https://forum.freecapitalists.org/t/libertarians-on-kissinger/11733/33
I was curious too. To me it seems Dave’s posts there were uncharactaristically emotional (as opposed to the usual pithy and rational), deriding Rothbard with terms like:
“raving like a madman, or a paid propagandist”
“totally from fantasy world”
“he is lying”
“He lies about the numbers”
“Rothbard also gleefully accepts fairy tales”
“Rothbard doesn’t bother”
“people are very interested in lying, and Rothbard is very interested in publishing their version”
All basically for not reading the Wikipedia article (for an essay he wrote in 1987) so he would know the politically-accepted number of deaths.