Canceling bar mitzvah celebration as punishment for wetting the bed?

My son will be 13 in a few months and he still wets the bed almost every night. According to halacha, he'll still become an adult whether there is a ceremony in shul or not. But he certainly isn't a "man" if he still wears diapers to bed. I'm sure you can imagine how I feel having to buy him "goodnites" at the supermarket. I fill up the cart with other things, then go to the diaper aisle, look around to make sure no one can see, then I put the goodnites in the cart under other things. Is taking away his bar mitzvah an acceptable punishment? Of couse, he can have the party as soon as he starts waking up dry.