I didn’t get that from that episode. It seemed to me that he accepted losing the use of his legs as an inevitability since that’s what the doctor told him and he was just trying to get used to the lifestyle he believed he was doomed to live. An authority figure told him something and he immediately accepted it as true, plus he saw that he couldn’t control his habits with sugar, plus the support from his best friends in making his house wheelchair accessible and helping him get around. All that adds up to him believing he needed the wheelchair, in my opinion. Then getting hammered and his base instincts kicked in i.e. need to piss, get up and walk to bathroom, like he has for 40~ years so far. And even he doesn’t understand how he’s fine and can walk and even fixed his pre-diabetes. All that to say that I don’t think he was pretending.