No one comes out of this looking good. With misgivings, Han is going to vote for category two, in the hopes that the arbitration officer might make some difference. He's not holding his breath, though.

The rest of his reasoning he's keeping to himself-- even if Rinzler's not technically a droid he's more like a droid than like anything else, and punishing him with time in solitary doesn't seem like it'd be effective. On top of that there's definitely at least some element of self-defense here... And he's been working with Rinzler for a while now with no hint of this violent side, so it seems like there's more at play than he understands.