There are events in this world that permeate the public consciousness. They are so big that they make all other topics seem irrelevant. Michael Jackson, whose prime was before my birth by the way, is the Icon of icons. His exit from the world is a once in a life time event that affects everyone.
I choose to make Hacker news my community of choice because it’s a community that holds rationality above all else. It is not rational to stick to strict rules no matter what. The corner stone of a community is shared experience and an event that has a profound effect on almost everyone should surely justify a rare exception to the "Tech only" rule.
So, if we assume it is rational to occasionally put the rules aside, the question becomes "is this event big enough to justify such an exception?" As has been pointed out several times here this story is the lead on every news based web site in existence. It’s being covered on every news station and even radio stations built around aloofness (JackFM) have dedicated commercial free hours to play only Michael Jackson music.
To me that signals an event that justifies a rational exception to the rules.