There are two aspects to this. The idea of entering a black hole for computational reasons, that makes perfect sense if the proposed physics are possible. But as an explanation of the Fermi Paradox, it utterly fails. The problem with this sort of theory is that you just need 1 subgroup of 1 civilization that goes the galactic colonization route, and you have aliens everywhere. Even if black holes are the most productive for civilizations to go, arguing that this is the reason for there not being ETIs is like saying that all life on Earth should clump together in the fertile zones. That's just not how it works - every niche is filled with life. I personally think that (ignoring the black hole option) a highly likely scenario for humanity is converting as much of the solar system into "computronium", and whatever posthuman and AI entities will occupy that will have very little reason to go anywhere. In a virtual environment thinking at incredible speeds, if FTL can't be broken the vast distances will just make anything outside of the solar system uninteresting. But going from there to saying that there's no chance of anyone having different ideas and taking off to different solar systems? If you have the energy and mass for it, you could just be stored for the travel and be kings when you arrive - but no one would do it? Nobody would worry that another galactic civ could develop and become a threat, and launch replicating probes to construct a galaxy-wide defensive network? Or that a fascination with the physical world and empire building remains with us and we colonize the galaxy because we just want to? The odds of these and other similar scenarios are certainly far enough above zero that an optimal non-colonizing civilizational goal just isn't sufficient to explain the Fermi Paradox.