It's not just this instance, I've noticed in an increasingly broad variety of topics that when something goes against the accepted groupthink it is prone to silent downvoting. Even in the absence of ad homs, whining in general, etc.
Also you'd be pretty hard pressed to say that this question isn't expressly relevant to the original article being discussed, and isn't overtly political in the sense that noone is agitating for votes or any such thing.
I was muzzled for arguing that Craigslist middlemen are bad. Then again I did say some things so out-of-bounds they should not be heard:
"Do buyers and sellers go to this man the way people go to real estate agents for their services? What would Craigslist buyers and sellers think of what he does if they knew about it? Respectfully, I think they would strongly prefer he weren't interfering."
That's exactly what I'm talking about, and the main comment I made that was at +4 when I went to bed last night is now at just +1 so I take it as fairly obvious that this people trying to muzzle well presented / supported positions that they happen to disagree with is really going on. http://news.ycombinator.com/item?id=3596880 also was in a tug of war between 0 and +5 for a few days but has settled now on +4.
Two in just the past hour with a quick look at recent comments + one 40 days ago where I noticed it first started happening;