People who frequent HN are likely to be part of the set of people who have been influenced by popular culture, which is a superset of David Bowie fans.
This would imply that all/most posts about popular culture figures are highly upvoted in HN but I doubt this is the case (no data, just subjective impression).
I think it just implies that HN users are informed by popular culture. Not every cultural figure is likely to be as important to HN users as every other, but some[0] clearly are, and posts about deaths are of a different sort.