The girl who says 'like a family' is just giving a heads up....to him, people around him etc.
There's another thread where a guy is being pressured to date a coworker. He should use the line, " but she's like family".
It might help. I don't know if it works for guys to clearly state intentions(lack of) or not.
It seems like it is still a respectful and appreciative thing to say to be clear about intentions with communicating with the opposite sex you're not interested in 'that way'
Maybe its not with certain male personalities.
How would a girl know? The guy its said to, would ideally retort immediately he doesn't like being called that, like Robert28 did.
That's authentic.