Re: Religious Restrictions on Training
It would be, practically speaking, a major issue in my dojo. There are frequently only 2-4 students at a given class. A class with one male and one female student who cannot work together is going to be frustrating. The instructor will have to split his time between them. (And a hypothetical class with a man who won't touch women and a woman who won't touch men can't be taught at all, unless you can bring in a second instructor.)
Additionally, some of our instructors, including our head instructor, are female. Because we are a Ki Society dojo, physical contact (in ki tests) between instructor and students is continual and centrally important. There is not always a senior male student present who could substitute in giving ki tests, and omitting the ki tests would, in our style, be a major detriment to the student's training. Not being able to take ukemi from the head instructor would also interfere with our aikido test protocol.
Finally, during the larger classes it is impossible to completely prevent physical contact between non-partners. The dojo is small and collisions just happen. There is no way to have a "males only" section of the small, square mat we use. Even trying to enforce this would likely leave the women on the mat feeling cramped and intimidated.
The alternative would be an all-male class with only male instructors. As we have no "spare" instructors this would mean that women like myself would have to give up 1/4 of our current training hours to free up an instructor for this student. I know in my case this would cause resentment.
I won't commit one way or another to the question "should this be done?" but factually it would be very hard to do. It's not like omitting the bow to the shomen. It would interfere, in a small school with a female head instructor, with a large proportion of what we do in class.
Matters could be quite different if the dojo were so large that offering male-only classes was relatively easy, or so male already that they tended to occur anyway. It would be easier in a dojo that did mostly pairs and not lines, circles, or randori. And it would probably be easier in a non-Ki Society dojo. I think this one has to be up to the individual dojo.