This. When I fought him I didn't let him talk. There was no justification that that character would accept or any explanation or apology that would placate him. I dropped the synths and attacked Kellogg.
Since the dude I'm currently playing with was an intel anolyst for the USArmy during Anchorage he's more level headed and pragmatic and will give Kellogg a chance to explain himself. Looking forward to seeing how that plays out.