He must have the last plastic MacBook (4,1), which has a 32-bit EFI firmware and will not boot a 64-bit kernel; Mountain Lion only has a 64-bit kernel. So, eve

He must have the last plastic MacBook (4,1), which has a 32-bit EFI firmware and will not boot a 64-bit kernel; Mountain Lion only has a 64-bit kernel. So, even if one thinks it should run Mountain Lion, it can't run Mountain Lion. End of discussion. If he wants to actually run Mountain Lion and develop for iOS (instead of complaining that he can't do it on his current machine), then $850 at the Apple Store will get him a refurbished MacBook Air (last year's model) that will be probably be much nicer to use (it will certainly be much lighter and have longer battery life). He could probably get a couple hundred bucks for his old one if it's in decent shape.