Yes - I agree. Sawyer was hateful and acting illogically, out of sheer rivalry I believe. I think he has come to believe his new persona, which is basically founded in two pillars: his committed relationship with Juliet, and his respected role as leader in Dharma.

He even refers to the Dharma folks as 'his people', while Jack is asking him of a solution for them, not anyone in Dharma. So Sawyer confronts the fact that his leadership is just mock leadership. He isn't even being a leader to the right people, especially because he is even pretending to be someone he is not, contrary to what Jack did.

The dynamics of Sawyer/Kate establish that for Sawyer, having Kate back is a reminder of who he really is at core. It makes his relationship with Juliet shake, but it goes deeper than that. it makes his whole new persona crumble. Seeing Kate again reminds him of how much he isn't Jim Lafleur. Of course, the same thing goes for Jack. Jack feels a threat to his new role as a leader but also, as Kate, they both look at him directly in the eye and call him Sawyer. They remind him of the fact that he is living a lie and that it comes with an end date. So he acts defensively. And mean. And honestly - like an irrational bastard.