From what I've read elsewhere the IJF is launching it's own promotion of professional fights, Gi with MMA type gloves by all accounts. So it makes sense that they would ban Judoka from competing in what will be a rival sport. They will need the fighters for themselves.
In the UK Judo has always been one of the most popular martial arts, has had a huge following for decades, well over a century actually, we have one of the oldest Judo clubs in the world here. The emergence of MMA has had little impact on it. I know too that is has always been tremendously popular in Europe, France especially.