No, Max really is that stupid

In season 4 he claimed that his near total divorce from reality was just an act to fool people into thinking he was a cloudcuckoolander in case he ever let slip that he was a wizard.

Problem is, in an earlier episode, he DOES tell someone he's a wizard, and when she doesn't believe him, he takes her for a ride on the family's magic carpet to prove he is one. And he was old enough to know better. The entire family, including Teresa, had to put their heads together to clean up after the mess he made.

He has moments of clarity, and a few moments of ingenuity, but he's mostly just an oblivious, brainless dolt.

"Does your society have any other adjectives besides great?" - Pvt. Church