I don't think it's such a big deal. Hey, if he shows up to a class with a female teacher or the class consists of mainly women, well, I guess HE has a decision to make. He can decide not to take that class.
In my dojo, there aren't a ton of women, so I don't think it would be too much of a burden on anybody, except the guy himself. It might make it difficult once he advances and can't participate in freestyle, etc... I'm certainly not going to sit out so he can practice, LOL.
To be honest, I don't want to work with someone who doesn't want to work with me. anyway.