Thanks for the play by play recap, though I'm not really sure it was necessary. He asked a question, I responded; though apparently not to your liking.
I would also strongly disagree that it is an ad hominem attack, as I am not attacking him, but his position. The best argument would have been that I was building a Straw Man argument or making an appeal to emotion, either of which I may have conceded, but certainly not an ad hominem attack.
The comparison of this position of refusing admittance to segregation is also a fair one, in my opinion. Now, just as then, many had strongly held beliefs that they were somehow morally superior to those of black skin, and by allowing them to comingle with their kids, they would somehow contaminate them. How is this different than the opinion that girls, gays, and trans are unworthy of being Scouts and going to dissolve everything BSA has achieved?