I'll bet he could tell you within a couple % how many offensive drives stalled, or defensive series gave up points, when giving up a 15 yard penalty. Hard to quantitatively assess the positive value you get out of the kind of hits that would be penalties if only the ref was watching, much easier to see the negative when they do call it. Guessing he prefers avoiding a known drawback over gaining a nebulous benefit. Same mindset why Jackson was the preferred player before injury and transfer, low variance, sort of the Hippocratic Oath of QB.