@JMO,
"Note that I said that when I stop making sarcastic and witty posts, not that this post was necessarily either."
The mod team apparently has real problems with contextual reading -- which may explain a lot, actually. When, in this context, you say, "the day I stop being sarcastic and making witty posts is the day you need to worry," you are, in fact, implying that you were engaged in at least one of those activities in the post in question. (Otherwise, once again, your post would be completely nonresponsive). As for sarcasm, I would say that your post falls more into the category of direct abuse than anything as clever as sarcasm, but as you say, that's a matter of definition.
Once again, I disagree that "Oh no, a rich white guy died!" is clearly demeaning (of the decedent, anyway). Calling somebody a rich white guy is not an insult, at least so far as I'm aware. I think it's fairly clear that the sarcasm in SYnapse's post was directed at the choice of which death to decry, and was not meant to be directed at the person killed in this case.
His point was very similar to the one made in this comic:
http://thehumancondition.wikispaces.com/file/view/examinercartoon.jpg/148030647/examinercartoon.jpg
I'm sorry if you can't distinguish that from not caring about the person's death.
Finally, I didn't "miss" the other reasons you gave. I responded to the one that you singled out as the one that actually motivated the remark.