I have sung countertenor since 1966 and have more than once felt the insult of gender discrimination. Regardless of one's musical tastes, it is simply wrong for the same reasons it's wrong to exclude women from practicing medicine. However you dress it up or rationalize it, gender discrimination is what it is. In California, it's illegal as to professional singers working for a non-religious employer. When public funds or facilities are involved it's illegal, period. I'm a lawyer by trade, and I'm itching for the right case to litigate this issue, which I'll gladly do pro bono. And by the way, the Episcopal Church has a specific canon against gender discrimination in all aspects of lay ministry. This isn't a musical taste issue, but a human rights issue.
I don't accept that this issue has to be about gender discrimination. Vocal performance is about more than just the tessitura. The timbre of a countertenor's voice is quite different from that of an alto, just like the timbres of a harmonica compared with a clarinet. No one would suggest that it is discrimination to prevent a harmonica player from auditioning for an all-state orchestra, even though that player could play the same notes as a clarinetist (or flutist or violinist). This issue is not about male versus female, it is about blended versus unblended tonal colors. Others have made the argument that countertenors can blend with female altos or sopranos, and I can accept that possibility. I can also accept the possibility that the Texas Board was influenced by gender stereotypes in making their decision, which is wrong. But to assume that this has to be the case, that is unfounded in my opinion. The Episcopal Church sees no contradiction between its canon against gender discrimination and its many Men and Boys Choirs, which do not allow female membership. Nor with its Girl choirs which do not admit males. Neither do I.