One of my best friends isn't liked by many people, including my parents. I've always liked her. She's abrasive, opinionated, and completely and totally honest. Which, for someone like me, is just utterly relaxing. I never have to guess with her. We've been friends for nearly 20 years.
My parents HATED how controlling, my way or the highway, and complete and total lack of tact she had as a child/teen (as an adult she'll use tact only as a last resort, and not for long ;). The thing is; she doesn't ever hold "the highway" against someone. She knows exactly what she wants, and if you want to come with her, great. If not, she'll see you tomorrow... with no ill will. There is no RESENTMENT with her, no backstabbing, no passive aggressiveness, no "should I call?", no "should I say something?" with her. Hurt feelings are an accident, and easily acknowledged and sorted. Any problem we've EVER had gets dealt with immediately, or tabled as "We just happen to believe two totally opposite things, eh. Whatever." and then are no longer an issue. I love her deeply, and she loves me in return, and either of us would (and have) fought tooth and nail for the other.
Personality types are interesting things. On the surface, we couldn't be two more different people. In another person with the same personality type as my friend, we might never have been friends. But with HER... we blend. We support each other. We are BETTER for each other. We're synergistic; our whole is greater than the sum of our parts.
This boy and your son may have been the worst combo ever. This Steve, however, may be the best friend in the world to John, and vice versa. Or they may not.
Regardless, I think that's their journey to discover, don't you?
We're not talking sociopathic tendencies (killing and mutilating small animals for example, which I would warn about), we're talking about a personality that completely and totally steamrolls over your son's. A guardian whom you disagree with their priorities. Those are both just personalty conflicts.