Humour is a coping strategy. If people are not allowed to make jokes about stuff that scares them it gets much scarier for them.
Oh, fuck off.
Most of the time I see that argument parrotted on Slashdot, it's being intentionally misused some borderline sociopathic asshole that's just made an insensitive joke about something that happened on the other side of the world and been called out on it.
Sure, we all know that you made that sick joke about that tragedy in the Philippines/China/wherever that'll never affect your home in Buttfuck, Illinois (which you'll have forgotten about by the time you move on to the next news item) as a "coping strategy". It's because you were scared by it.
We all know that people closely affected by events (or feel themselves likely to be affected) often take solace in black humour- fair enough. We also know that many people are just dicks that like to make sick jokes about stuff that doesn't affect them personally. Anyone in the latter group trying to justify themselves and place themselves *above* their critics with a self-righteous appropriation of the "non-PC coping mechanism" argument is full of it.
Live with it.
He's 90 miles from the site, he's closer to living with it than you are. Unless you're actually living in the bloody reactor, I think he's more entitled to lecture people like you than vice versa.