@Meet.. Cutie It's not that he doesn't appreciate the gestures, he just is foreign to them. You already seen that his family and him are not that close. He doesn't really talk to friends, and the only person he really talked to was Jaehyuk. Plus Jaehyuk knows Garam is foreign to his new behavior. You expect him to just forgive him when Jaehyuk, would SA'd him and even blackmailed him. Please remember that, either way after the hospital visit, Garam was letting down his guard slowly by he was. When they banter and pick on each other; that's a form of them bonding. It's not a uncommon thing.
Picture is from S-Kinnaly from Twitter. Character is Ganondorf the Demon King from Tears of the Kingdom.