You misunderstand, Dave.
Nobody said that you told him to literally kill himself. What you literally intended is beside the point.
There are things that can be said to people in not so sound mental states, that can cause them to self harm, or worse.
And lets be honest here, he wasn't exactly the most level headed person in the world...
You might think it's a joke, but you know literally zero about his circumstances.
You should be more careful, because for all you know, he could be suffering from manic depression (bipolar disorder).
I mean, sure, maybe 999 people out of 1000 would brush off a statement like that, but you don't know if your talking to number 1000 or not. It's such a dangerous thing to do.
It's nothing to do with living in a "bizarro-world". People kill themselves in the real world and it's no joke.
He clearly took offence to what you said.