I suspect, given the general tone of the piece, that the word "loser" was being used ironically in this case (as a mock of the way a football coach would motivate his players) and not in the sense of the reader being an actual "loser."
I also suspect that if the escort knows it's the guys first time, he'll know to stop fucking when the guy cums. I took this article as advice for the client, not for the escort himself.