He's not a slasher per se. What he is is a crazy granola-fed leftist pastor, so he looks at it as a willingness to explore love and healthy, open expression of fellowship even across artificial boundaries in a genre (and society) that generally fears and limits emotional expression between men and ignores entirely interaction between women.
To which I responded, "also, it's all very gay. Destiny/Mystique is even canon." And he acknowledged that that, too, made Claremont pretty cool.