Robert Morris: The Yellow One's the Sun

Preachers, think twice before you use other people as illustrations.
Easter Sunday at Gateway Church Robert Morris preached about Jesus as the Son of God (link to the sermon on the Gateway site). He speculated about Jesus and the Father playing catch with the stars and Jesus creating the Earth as his school science project. Apparently Morris delivered the sermon to more than one crowd because the sermon on the website does not appear to be edited. However, in another delivery, Morris added a little joke (apparently a rip-off of Brian Regan) at the expense of the kid in school who isn’t “the brightest kid in class.” Watch:

Now, the depiction of the Trinity is troubling here. Is Jesus God’s little boy?
Readers who have experience with Morris/Gateway: Is it common in sermons to poke fun at less fortunate folks? I don’t want to seem picky but the disabled are stigmatized enough already. I doubt parents of kids with intellectual disabilities saw the humor.
Readers: Am I overreacting or does Rev. Morris owe his audience an apology?