I don't think the poster is objecting to the slash - it's just that everything is so sexualized now that themes like familial love and friendship are constantly being undermined. This is in part why I left the Supernatural fandom - I was discomfited that the majority of fans can't seem to enjoy a close sibling relationship without superimposing an incest subtext upon it.
Similarly, I also feel sometimes that beautiful friendship stories are ruined when you throw sex and romance into the mix. I've learned not to make a big deal of it anymore (esp since comics make me want to pair everyone with everyone else!) but I understand that it can be frustrating sometimes. :)