At this point, I think you are rationalizing your intuitional dislike of the article.
Maybe you're not understanding me, and maybe this is partially because you're new to the community...
But when I visit HN, I don't want to be presented with the 99.99% of speculative trash that fills the internet. I can go to Digg or Reddit for this sort of junk science that gets us intellectually nowhere. I (and everyone else) want to see that quality .01% that presents legitimate scientific inquiry, regardless of whether we agree with it or not.
I think you don't get it. Speculation is not the same as junk science. Speculation can be insightful, interesting and intelligent or it can be the opposite. Obviously you thought it was trash and just as obviously a larger number of HN'ers thought it was good. You seem to arguing that everyone else should use your criteria for what should be on Hacker News.
Actually I had a look at a few of the guy's other articles and it seems he is a little loose with his facts. I love good speculation and I thought that article had some. But the author often does seem to miss the distinction between fact and opinion. Still you (kirse) should be prepared to back yourself up if you are going to label the article as trash.
We're a long way from being able to tell why animals developed the traits they did through evolution. We're a really long way from being able to empirically prove it. That doesn't mean speculation isn't fun in the meantime.