First, I value friendships with real people. If I were an em, I would probably value friendships with real ems and not unconscious simulations.

If I valued torturing real people, em-version of me would probably value torturing real ems and not unconscious simulations.

Not all humans have pleasure as their summum bonum. Not all humans would want em-bliss.

Second, you do not know what this screening process would entail and whether it would be possible to fool it. You also do not know how unfriendly neurotypical ems could become.

Third, yes. Em-hell is unlikely. However, if it is possible for a monster-em to arise and gain power, Pascalian reasoning begins to apply.

Fourth, em-hell and em-heaven are both fantasies. Other hypothetical futures probably deserve more focus.