The plan currently revolves around using Connection Theory, a new psychological theory, to design "beneficial contagious ideologies", the spread of which will lead to the existence of "an enormous number of actively and stably benevolent people", who will then "coordinate their activities", seek power, and then use their power to eliminate scarcity, disease, harmful governments, global catastrophic threats, etc.
That is not how the world works. Most positions of power are already occupied by people who have common sense, good will, and a sense of responsibility - or they have those traits, to the extent that human frailty manages to preserve them, amidst the unpredictability of life. The idea that a magic new theory of psychology will unlock human potential and create a new political majority of model citizens is a secular messianism with nothing to back it up.
I suggest that the people behind Leverage Research need to decide whether they are in the business of solving problems, or in the business of solving meta-problems. The real problems of the world are hard problems, they overwhelm even highly capable people who devote their lives to making a difference. Handwaving about meta topics like psychology and methodology can't be expected to offer more than marginal assistance in any specific concrete domain.
There's only one way I was able to interpret XiXiDu's top comment (the one you link to), and that was as a satire of responses to his many previous questions about SIAI. I can't read it as a slander against Leverage at all. To me, this thread is roughly equivalent to attacking Jonathan Swift for his policy of baby-eating.