I did have a moment of shock at the way they played that last scene, more I think because I did see some potential for redemption in Michael than because I thought 'OMG, he's not culpable for his actions, Teyla's a murderer'. Thinking about it, though, I don't think he ever intended to allow the Atlanteans to live whether Teyla came or not. And I absolutely agree with what you've said about how he's entirely responsible for his crimes - the Atlanteans made mistakes in their treatment of him, but in no way is it even conceivable to blame them for what he went on to do. If his arc had been handled differently maybe he could be seen as more victim than villain - there were points early on when I thought they were going to take his character in that direction - but the way it stands I struggle to see how anyone could buy his denial of his own guilt.

I guess I'm not really sure what I think. I'm not really comfortable with the idea of summary executions, but nor would I call what Teyla did 'cold-blooded murder' or OOC. *ponders some more*