HN's voting "thingy" is obviously engaging a middle-ground positioning, especially when it comes to political views. Moreover I suspect that arguments are taken more serious when putting some "I try to be aware of my biases" upfront.
Especially among (more or less) non-political communities like this one an argument starting with a"I am an independent voter" premise is most likely going to get a better reception than a "I have been for years a dedicated follower of politician x". Not that I am a fan of this, quite the opposite - but there are other sites much more suitable for political "confrontations".
I'd hesitate to describe HN as non-political. The majority of HNer's are very pro-capitalist and pro-business from what I've observed, which makes sense given the community's focus on start-ups. The popular political sentiments that you'll find on Reddit are very different from those you'll find on HN.
Especially among (more or less) non-political communities like this one an argument starting with a"I am an independent voter" premise is most likely going to get a better reception than a "I have been for years a dedicated follower of politician x". Not that I am a fan of this, quite the opposite - but there are other sites much more suitable for political "confrontations".