No authoritarianism. The movement is comprised of numerous people. The general foundation is focusing on making the world a better place; many different directions are encouraged. A sensible metric is something akin to "well being of sentient life forms of today and the future". If you have a different direction than the movement, that's fine. What the movement can do for you is to help you pick ways of helping others that cost less per-dollar-donated or per-effort-spent.
It doesn't need to be a one-person dictatorship to be authoritarian. How long before this is coopted by politics that limit charitable spending on anything but projects that are "blessed" by this group?
No one is forced to stay inside Effective Altruism. You can be an Effective Altruist without calling yourself one. You give to charities EA recommends without subscribing to even half of what EAs care about. If EA is "coopted by politics" I suspect many people will leave and the movement will become a shell of what it currently is.
Consider learning more https://www.effectivealtruism.org/