Something I think that needs to be pointed out is that the safe call is not only designed, imho, for the sub but should be in place for the Dom/me too. Just because the power may be seen in the other direction that still doesn't mean that the Dom/me isn't meeting a serial killer as well.
I know most Dom's, who insist (and at times demand) that any sub they meet have a safe call, then don't take the same precautions themselves. That to me makes no sense. Can I over power a man with physical strength? Probably not. Could I drug him or have a friend waiting to ambush him.... absolutely. (NOT that I would but you get the point...)
Anytime, you are meeting someone new, no matter how you met, your role, or your sex, in my mind, a safe call is the only way to go!