Yes, it is incredibly disrespectful for friends to be drinking to and at their deceased friend's memorial service after he died of alcoholic behavior. Unconscionable behavior, indeed. But, worst yet, they are in denial. These were probably the same people who encouraged the guy who died to drink (not that they are responsible for his death, mind you).
I agree with you. 100%. But, do not expect immature students to see this for what it really is. Perhaps these people who do not see the irony in what happened at the memorial service are downplaying it because it reaches way too close to home in their own drinking habits.