Not altogether sure, no JS, but when Paddy was four, we acquired my lost boy - Flynn. He was an 8 week old kitten, and Paddy really couldn't stand him. He'd go out if Flynn came in and he'd run off and hide when Flynn tried to play. We had Flynn for 4 years before he went missing, but after he'd gone, Paddy became a much happier and more settled cat. With him being old and with all of his health issues, I'd feel awful if he couldn't feel settled and comfy for his remaining time left to us. I know he wasn't supposed to see December, but he did, bless him.
Having said that, when we were looking after a 3 month old kitten of a friend, Paddy was more curious and off-hand than outright offended, although maybe he knew he wasn't staying for long.....
It's horrible this, 'cos he looks such a canny little cat, and I know Tess would be no bother with him. Not sure about OH though.....