He's right.
I know I'm mental because right up until that point I was nodding with Josh's comments.
What I mean is, he's not 100% right. His approach, in theory, is nice, but it becomes a bit more complex then that, unless everyone abides by the same rule.
It doesn't matter if you're nice to everyone because when you get down to it some people are just jerks. And somehow these jerks always seem to get friends. Now their friends may be fine, completely normal people you get along with well, but regardless of that the one person will be a jerk and no amount of being nice can change their opinion of you. At that point it's best to distance yourself from them at all times.
Others times people can react differently in different situations, jealousy and such can become more serious when alcohol is introduced and the whole system begins to fracture as everything starts to go wrong.