1) Sure, people often have own distinctive style of writing and use it consistently, whatever the theme is. To change it is not so easy. I don't believe that Singularity will ever happen, but I have no problem in agreeing with some other Eliezer's opinions because he defends them with the same eloquence as he promotes the Singularity.

2) A cynic can be right about his ulterior motive, but it is difficult to judge other's motives, and it's also only marginally relevant to the truthfullness of his writings.

3) As I understand it, this post is about mutual cooperation when the costs are very high. It doesn't endorse violence against opponents.