Interesting, you find my comment to be fairly ad hominem but you don't the slide deck you shared?
Basically all the "data" and arguments that he's presenting are cherry picked to be on the edge of plausibility, but as soon as you poke at them at all they fall part. It's really just a standard piece of denialist schlock.
For example on slide 4 look at his plot and compare to the wikipedia page:
https://en.wikipedia.org/wiki/Description_of_the_Medieval_Wa...
It's a bunch of canned and repeated arguments that are easily shot down, but doing each one takes so much time. It's like "debating" a creationist, shooting down an argument means that many more easily shot down arguments come right back up, with the denialist side somehow never loosing credibility while trying to assail the credibility of others.
If somebody finds that slide deck interesting, please read other data too, it's a completely biased picture, meant to trick people. Something balanced like the IPCC will be far more solid information, with proper citations, that can be backed up.