Even if supermassive, primordial black holes are wormholes, there's the whole issue of the universe possibly ending juuuuust before you reach the event horizon, due to relativistic time dilation making time pass almost infinitely slower near the event horizon vs. anywhere further away from the black hole. If you survive the blue-shifted irradiation dosage. If the black hole is sufficiently large that you aren't ripped apart at a sub-atomic level. It's fun to imagine in-situ observations of an event horizon in an attempt to validate theories. It's fun because it doesn't even make sense, even if you threw something microscopic down there on a perfectly massless fishing line.
As it turns out, you are wrong about this every October 9th. Also, because search is occasionally awesome, Kardashev Arms.