There's various things, but one of the main problems these people probably have, as some of them are AI researchers/simulationists, is that the real goals of the AIs are very unclear. Simulations at a very high detail either work and are widely used or are faked (causing horrible implications if they really are faked), so it's likely the AIs use simulations in planning. It's even worse if the simulations are not faked at all, as the AIs would run thousands or millions of simulations of really horrible situations, testing different interventions. If they are trying to reduce suffering, even not as their sole concern, why are they doing this? If they aren't trying to reduce suffering very much, the mind control is not really in the "human"'s best interests, it's just to control them.
