The lights are on
hhmmm...get him what he wants. You asked him and he gave you a response.
Well, look at it this way. How would you feel if an older brother (or parent) asked you what you wanted for christmas, and you asked for a PS3, but they get you a 360 (or Wii) instead because they saw you have fun with it a couple of times? Sure, it's a really nice gift, but it's not what you really wanted. Sure, you'd have to be completely spoiled to complain, but you'd be happiest with the PS3, wouldn't you?
Besides, if you both live under the same roof, you'd both be getting the best of both worlds....well, unless you're being secretly selfish and want to dip your hands in a potentially larger pool of family owned PS3 games.