Zontar said:
The vast majority of the people he killed when trying to escape where unarmed deck hands and a tower crew who where no threat to him and had no ability to defend themselves. Under current international law regarding war he'd be considered a war criminal.
Not really. A uniformed combatant does not need to be armed with a personal weapon to be a legitimate target, if their role in the organization means they are crewing or maintaining a larger weapons platform. As such killing deck hands on a military vessel while trying to escape is completely alright, as they are keeping the Star Destroyer and/or its' TIE fighters functional. Had they taken steps to show their intent to surrender it would be illegal, but none of them does. The people in the tower also explicitly try to stop the escape by operating in their capacity of communications and logistics specialists, which makes them legitimate targets.
If your interpretation of international law was correct, it'd be a war crime to sink any ship where everyone in the crew didn't have access to a personal defense weapon. It isn't, as the ship itself
is the weapon and anyone aboard is counted as servicing the weapon. The only exemptions to these rules are medical personnel (including field medics) and chaplains, who are to be easily identified via designs on their uniforms, but even they are considered acceptable collateral damage if aboard military vessels or near military targets during combat or when attacked by weapons that doesn't discriminate between victims, such as artillery and grenades.
As for the threat part: Poe was exercising his legal right to try and escape and evade capture (as provisioned in the Geneva convention, all PoWs have the right to try and escape captivity and return to their own military), which means that anyone that can undo his escape attempt and belong to the military of the enemy is a threat to him in that situation. Even if they are unarmed, they can call on reinforcements that are not and as such they constitute a) a uniformed combatant and b) a threat to Poe's mission which makes them legitimate targets.