Whether being a jerk justifies banning I can't say - but his assertion that HN is biased has little justification (particularly when you consider that the writer himself is biased.) Kindly ignore.
It kinda comes down to what sort of "thing" HN is supposed to be -- whether it has a place for people like him -- but regardless, he's certainly not exactly hurting over his inability to play in our little sandbox here.
Knowledgeable he may be, but professional he is most certainly not.
Edit: I must admit, however, that I'm interested as to why he was banned. I don't believe he's said/done anything spiteful and mean in HN itself.
He's been a major drain/drag on the Node.js community, and makes the IRC channel a toxic wasteland for a good part of the day.
He trolls other sites as well... http://www.youtube.com/watch?v=IrkDqh9ZVog
I find his hook.io project (http://hook.io/about.html) particularly interesting, and the BDD testing app he was building for Node Knockout has a lot of potential as well.
Marak comes across as someone who's seen that and intends to emulate it, without the actual development skill or talent to back it up.