I don't know. He's just being pedantic, really. I'm always wary of someone who reaches for a dictionary to solve an argument; dictionaries only contain certain words and usages.
Prides, to the best of my knowledge, do not exist to make LGBT people feel special - to a certain extent, they do the exact opposite. They tell the rest of society that such people are normal and that there is nothing wrong with being queer. It's pride in the face of a society that thinks less of you for being gay.