It's still a reason, even if it's a stupid one.

[His voice is firmer now.] ...Hate's a good enough to do anything and Archer's earned it anyway. He's a stupid Rocket and he hurt someone I- I care about. You.

I'll make sure he doesn't do it again, too.

[There's something dark in his voice now. As if he really will make sure Archer doesn't ever hurt Archie again. At least not while Niko's here.]