Ten minutes later he hops in a tie fighter and blows up thirty of those comrades with no respect for their lives whatsoever.
Because they have no respect for his, or anyones. He is the one. He is branded as a traitor to all First Order soldiers, to be killed with high regard. He realises that the first order is not his place. If he had of gone down, no one would have comforted him. He decided to not fight for the First Order. Doesn't mean he won't fight against the First Order.