The joke certainly seemed to start as one about him. I tried to remove any political reference from my joke because a political reference seemed unnecessary and unhelpful in the current context. I do think it fits into the current context well with the political reference removed. And no offense to Brazilians intended, either. It's just a pun.
That said, I think that few people, on either side of the aisle, would credit GWB with being the brightest bulb ever to inhabit the White House. That honor has to be bestowed on Martin Van Buren. See:
http://en.wikipedia.org/wiki/Martin_Van_Buren