Discriminatory is not the word when talking religion. It is when talking the art (unless you see Aikido as a religion).
Why is religion elevated above the art? Why may a "religious person" who discriminates based on gender (and it is discrimination) offend another person, who may also be religious, of the opposite gender? What of the religious rights of the female half of the population?
And why create a special category for religion whereby the concept of discrimination does not apply? Especially against the historical evidence of discrimination by religions of all sorts?
And, yes, some people do view Aikido as a religion. (Not me, however.)