If Stick's old hobo appearance is fooling you, then he's winning. He's like Madame Gao, too smart for this world. He called Matty's place a shithole but he was trying to get a rise out of Matt, he wanted Matt angry and punchy. Stick wants Matt to leave the (not-shithole) flat behind, and the furniture, and the silk sheets, and the friends, and everything that is tying Matt to a normal life, because he wants Matt with him, off fighting a war.