The odd thing is that John himself inadvertently disproved this notion by marveling at a tendency to not let a fact he didn't feel like hearing sink in that he himself demonstrated. We get a further hint as to why Mike doesn't seem to make much headway with mathematics later on when another wise-ass who thinks that school is all about only doing things that please him when Liz's overseer tells her flat out that Dylan's math grades are in the cellar because a child has to actively want to understand math in order to do well.
We thus have to deal with the possibility that Michael simply suffers from a mental block that prevents him from wanting to understand math because it's hard and it's not fun and it's too much like work and life is supposed to be easy and fun ALL the time. It's akin to how John has a mental block that prevents him from understanding that it's not woman hormones that make Elly feel as if her life has no meaning because that would make him a bad guy who welched on a deal because he believed in a fairy story about some fake, impossible, bull-shit and non-existent thing called a maternal instinct that magically makes women love domesticity because he's too stupid to understand that his mother wasn't a grinning robot who mindlessly baked socks and knitted cookies. She CHOSE to do so because it pleased her and besides, someone had to. John can't allow himself to listen to complaints that require him to be a less self-serving dick because he can't face the possibility that he actually IS a self-serving dick.