If neither an infinite universe with the simplest topology nor a finite universe with a nontrivial topology make any distinct predictions, how can it possibly be a scientific question which one is actually true? An argument which uses "Occam's razor" is a purely metaphysical one if it is impossible in principle
to test whether your conclusion is correct (unlike, say, the theory that the laws of physics work differently on a single planet in the Andromeda galaxy, an idea which seems very implausible by Occam's razor, but which could in principle be tested directly). Plus, some people might argue that a finite universe is inherently simpler than an infinite one, and is therefore favored by Occam's razor even if it requires a slightly more complicated topology. As it happens, it could actually be possible to find experimental evidence for a finite universe by looking for repeating patterns in the cosmic microwave background radiation (see this page
, or this one
), but this would only work if the radius of the universe is smaller than the maximum distance we can observe.