What really is the difference between a singularity and a black hole? How can someone theorize a point with all the mass in the universe, without that point being a black hole?
So there is the technological singularity a la Kurzweil. In math, it's a function that goes to infinity and you can't do anything with it at that point. In physics, the only kind of singularities I can think of are stellar black holes, supermassive black holes and universes in some kind of giant multiverse.
IMO, when we're talking about all the mass of our universe being compressed into an infinitely dense black hole, we're talking about something that is many, many orders of magnitude more massive than a regular black hole and may therefore, perhaps, be a totally different kind of creature, as we've seen so many times before in physics when our focus changes by many orders of magnitude. Just my two cents; I'm definitely no physicist!