While I agree that the failure mode of being clever can be asshole, I really don't think that's the default failure mode most of the time. I wish he had provided some examples so I could have a clearer grasp on exactly what he means by clever and asshole.
I feel like the advice should be more like, "If you're going to be clever, make sure it's the right tone for the audience, and that the failure mode of your joke isn't asshole".
You're never going to know that for sure, the more important part is that if you're going to try being clever make sure it can't be misinterpreted as you being an asshole.
I feel like the advice should be more like, "If you're going to be clever, make sure it's the right tone for the audience, and that the failure mode of your joke isn't asshole".