Given assumptions that seem natural now. I don't actually disagree with those assumptions. But those assumptions are, in fact, assumptions. (Recall the bizarre topology example that permits for negative space beyond our lightcone.)

Given, furthermore, what the original question was -- P(Universe-is-Infinite) -- the question of whether there's even a 'something' out beyond the lightcone remains even-more-relevant.

And as I originally, I believe, said -- the low confidence interval necessary to properly express a Bayesian probability prediction in my opinion makes it far more 'appropriate' to simply say, "There is as yet insufficient evidence for a meaningful reply." (Or, short-handed: "It's unknowable.")