Even in an infinite universe there's no requirement for all events to have non-zero probability of occurring. A simple analogy: there are infinitely many intege

Even in an infinite universe there's no requirement for all events to have non-zero probability of occurring. A simple analogy: there are infinitely many integers, but even if you could pick between them all uniformly at random infinitely many times you'd never pick π. Not all events even have to be in the distribution of possible events. That's often not going to be relevant for evolution, since the distribution covers physically realizable events like adding DNA base pairs.