Why not show him that your photos are better even with an 'inferior' camera? Just in case you are wondering, photography is an art, not a science. The only physics knowledge you need in photography is that light is needed to make a photograph.I've come across a friend of mine who also has very high ego on his own camera setup and photos. Tried to explain some facts or knowledge I learned from books and websites to him because I saw the photos he took using Canon 7D and L lenses are blur, grainy and underexposed, but always ended up with quarrels. One of the reason he told me is that he is an engineer but I'm in banking so has better knowledge in physics than me
So I think as long as he is happy and enjoy the hobby, just let it be.