Yeah, probably. Would take more effort to get balanced, though, and using an equation to see how much it's counted for would make the code more complex, and harder to modify on the fly. It's not uncommon for spam to be alive for a while either - check /noobstories sometimes, stuff stays alive for a while. I suspect that most of the dead articles are killed by filters, looking at what dies and what stays alive. Doesn't much matter as long as it isn't upvoted, I think - the links have rel="nofollow", or at least this one does, so no pagerank is going to the spam site, and almost everyone here is savvy enough to recognize spam.

But hey, I'm just one user; if you want the opinion of the community, submit an ask hn about it, and see what the community thinks. Or go out on a limb and write a patch which would enable it, and see if pg accepts it.