I’ve met him a few times at small conferences and my ex used to babysit for him. I think he’s quite playful actually, in a very focused intellectual sort of way. He often goes extempore and makes contemporary jokes out of his presentations. This post too is sort of him testing himself on an unrelated topic, and the number of otherwise distinguished academics doing that is nearly zero (e.g. Roughgarden). But of course he has a very strong desire that the universe is actually just a manifestation of simple local rules (that would offer the best memory performance for the parallel processors in the simulation hypothesis, right?), and that all of mathematics can be replaced by the same.