Ruthless? Maybe the guy was ruthless, but the fine article doesn't explain why. This guy just figured out the rules of the game, and gets promotion after promotion because of it.

Is it ruthless or unethical to befriend people who affect your future? Of course not. Is it ruthless or unethical to lose touch with people? Nope, people lose touch with each other all the time; it's unavoidable. In this case, it's just that he gets promoted faster and makes new friends faster than what is considered appropriate.

Had he done the same thing but less efficiently it wouldn't be considered ruthless at all.