John scolded me and wanted me to explain why I couldn't do something.
Why did he scold you for that?
Because I didn't feel like explaining my views on the issue any further.
If you're unable to do something then you should be able to explain why. Otherwise you'll end up letting people down and they'll stop coming to you for whatever their needs are. This will in turn cause your relationships to become strained.
That doesn't matter to me. He's not really a friend.
Then you need to communicate that to John rather than misleading him about thinking you're friends, refusing to act like a friend, and not telling him why. That will just make him confused and hurt, while you get frustrated by being scolded. Wouldn't it be better to be honest and clear the air?