Obviously with a non medical background you are not qualified to JUDGE.
On both sides of the equation it depends on how the person, who has the illness, wants to deal with it, whether in a light moment or not.
This pillock is not making a joke of it, just saying he is a bit mad thats all.
I have a relative who has the same illness, who encourages to make a lighter side of it.
So unless you are of a medical background I would back off!