If that's true, it doesn't matter. There are so many other things to worry about. First of all, it's really no one else's business if Russell Simmons is transitioning to a woman. If as a public person, there's an announcement about it, fine, but it really doesn't affect anyone outside of his family and friends.
Someone's choice to transition is their own. Whether it is Richard Simmons, or Russell Simmons, it is their choice. Personally, if this is what someone feels they must do in order to be a happy, productive member of our society, then I would encourage them to do so. In the end, however, it is not for me to judge whether or not someone should transition to different gender than the one assigned at birth.
It is a personal choice if someone decides they want to change their sex. This is no exception for Russell Simmons. He has free will and nobody can stop him from making that choice. It does not matter if he decides to live his life as a man or as a woman.
It's their body and their choice, they can do whatever they want. It does not matter to anyone but themself and whatever loved ones they have. People may argue that him being a woman is a safety issue and whathaveyou, but that just isn't the case, and if he does transition, he was transgendered all along and this really hasn't come out of nowhere.