I look at the term to be a welcome clarification of someone's intention.
Let's face it, Hollywood and the outlandishness of the homosexual movement have turned normal language into dirty talk. So now the idea that when someone says something that could have double meaning but you want to make it clear you are being normal you say: No Homo.
I know in today's environment it is not possible for a man to tell another man he looks good in the abstract. There's too much "down low" and other deviant behavior on-going that is being fostered by the media to leave any doubt.
I don't know if this was the intention, but I'm taking it as a cultural stand against the negative drift.