I didn't notice any remorse in his eyes. But even if it was there, it would have made much more sense if they'd dwelt on it more. Slaughtering a bunch of kids who are jedi, when you cared passionately about the jedi very recently, warrants more of a response than slight remorse. It's incredibly hard to turn your back on something that you care a lot about, but even harder to start murdering your friends' kids.Are you just not listening? Young Jedi are still Jedi. You could see the remorse in his eyes before he did it. He was instructed by the man hiding the secrets he wanted to eliminate the Jedi without hesitation. So why would he leave any of them alive? What's so hard to see?
Someone in that position should be mentally anguished about killing the kids as a MINIMUM.