The bastard thought his would be granted parole? What a laugh. Even after all these years, he should really just learn his lesson and rot in prison for the rest of his life. Haneul doesn't need to open the other messages from Ahjusshi - the shelter owner, to know what is written. And so, he doesn't; opting to do so in the morning when he will reply as well.
Because the old man would know he had his nightmare and will start to worry if he does it now.