I guess I'm more looking for a response to "yes CFCs can destroy ozone even though they are heavier than air," and "here is a graph of the size of the ozone vs space shuttle reentries" that shows a non-correlation.
Also if you lie down on the ground do you suffocate to death because of all of that heavy ozone hanging around there? No, because it's dispersed throughout the atmosphere.
Ultimately it sounds like the kind of situation where no amount of logic is going to change his mind and that you're probably better off avoiding the subject entirely for the sake of your own sanity.