I really, really wish you could toggle off aliens. I have studiously avoided buying occult game packs, but Get to Work has...well, work stuff, which was the reason I bought it. Aliens were an unwelcome addition!
I only had the aliens attempt to abduct one of my sims once—used the resetsim cheat and stopped the abduction in its tracks. Whenever my sims get a moodlet from encountering a disguised alien, I go into Manage Households, find the offending extra-terrestrial, and edit their disguise to look the same as their regular-alien form so they can't fool anyone. If I kill them off, they'll just be replaced by a new disguised alien, and that won't solve the problem.
My sims, meanwhile, simply avoid socializing with aliens once they're outed. In my simworld's canon, "blueskins" are treated as a despised ethnic group, like the "untouchable" caste in traditional Hindu society or Blacks in the Jim Crow South. Which is...highly problematic by real-world moral standards, but unlike the real-world ethnic groups who had no say in their situation, the aliens abduct people and impregnate them against their will and disguise themselves to infiltrate human society. They deserve what they get.
