I am loath to judge the intelligence of people who run for office because we don't really know them. All we see of the candidate is through a bubble of prepared statements and handlers. They might do or say something stupid, but you can never know for sure if the stupid thing comes from some bad campaign advice, a mistake from the stress of the campaign, or some odd confluence of events that happens with any large organization with lots of moving parts.
BUT I just don't see how I draw any other conclusion from what Donald Trump wrote in response to Abdul Jabbar's WaPo piece. Maybe this is the exception that proves the rule.