He wants to do away with the "who are we to judge" attitude that allows good people to stand by and do nothing while other people (good intentioned or bad intentioned) do bad things to harmed people.
I get that. But, his viewpoint, employed by power hungry people, can be as dangerous as the live-and-let-live attitude he is fighting against.
The key for him is the maximization of the well-being curve, which he thinks can be objectively measured (thus, "science"). But, it may be objectively measured only to a point. There is a significant "moral uncertainty principle" which kicks in, and that is the intrinsic value of individual freedom. For me, I think there are two factors to maximizing the well-being curve: both kindness/goodness, and freedom. The moment I start substituting my perception of well-being for another person's perception of well-being, and forcing them into a so-called well-being curve of my own construction and not theirs, I open the door to despotism and great human suffering. Obviously he doesn't want that, but that is the side risk to his premise that "it is ok to judge."