It is entirely within YC's right to fund businesses that a portion of the Internet find scummy.
Shockingly, it's entirely within the rights of that portion of the Internet community to then whinge about them funding said scummy businesses.
And it's YCs right to care, or not, about that opinion.
Someone once wrote a blog post that had a paragraph on cheating (on your spouse etc) and what constitutes cheating. He said that it doesn't matter whether you think what you did was cheating, only whether your spouse thought you were cheating. Your worthiness is entirely in the eyes of the other person, not yours. The other person is who you're 'selling' yourself to.
And so it is with companies. If McDonald's customers suddenly care about healthy food, McDonald's has to too.
The question is, is the portion of the Internet community that thinks these people are scummy YC's spouse? Should YC bend to their version of reality?
That's for YC to decide.