Given that there's no definition for the value of a util, arguments about how many utils the universe contains aren't likely to get anywhere.

So let's make it easier. Suppose the mugger asks you for $1, or ey'll destroy the Universe. Suppose we assume the Universe to have 50 quadrillion sapient beings in it, and to last for another 25 billion years ( = 1 billion generations if average aliens have similar generation time to us) if not destroyed. That means the mugger can destroy 50 septillion beings. If we assign an average being's life as worth $100000, then the mugger can destroy $5 nonillion (= 5 * 10^30).

Given that there have been reasonable worries about ie the LHC destroying the Universe, I think the probability that a person can destroy the universe is rather greater than 1 in 5 nonillion (to explain why it hasn't been done already, assume the Great Filter comes at the stage of industrialization). I admit that the probability of someone with an LHC-level device being willing to destroy the Universe for the sake of $1 would be vanishingly low, but until today I wouldn't have thought someone would kill 6,790 people to protest a blog's comment policy either.