When left-winger insults right-winger, it's not against TOS, but when right-winger insult left-winger, it is. Curious, really...

That's quite untrue, and a bit an impetuous conclusion to jump to. We work hard at doing our job professionally, including not moderating HN for ideological reasons.

Of course we have biases, but (a) we consciously work at suspending them, (b) they're probably not what you think they are, and (c) one cannot accurately assess another's bias by consulting one's own passions.