If you dig into the details (there a link to an enormous *.gif of a spreadsheet), you'll find he gives a low, best-guess median, and high number for each democide he studied. The high number for China is 102,671,000.
Ah! And even better, I'm glad you brought that to my attention. He should update that table. Here:
http://www.hawaii.edu/powerkills/NOTE5.HTM
He has this:
IMPORTANT NOTE: Among all the democide estimates appearing on in this book, some have been revised upward. I have changed that for Mao's famine, 1958-1962, from zero to 38,000,000. And thus I have had to change the overall democide for the PRC (1928-1987) from 38,702,000 to 76,702,000. Details here.
http://freedomspeace.blogspot.com/2005/11/reevaluating-chinas-democide-to-be.html
Yeah, that's the fella I'd read a few weeks ago. I thought the numbers were higher...