Hello, I'm that just a regular physicist you talked about, I might not be able to explain how the Mæron works as it is a work of fiction but I can speculate on how it might work
First I'll try to give some feedback on your own speculation and then I'll give my own.
You are correct that time dilation occurs next to strong gravitational fields, however in theory this effect can be contracted by negative mass/energy, so I wouldn't rule it out
you mentioned how if it was a black hole tucker would be dead(his electrons would be scrambled?), could you elaborate on this?, im not aware of any reason for this as some black holes, namely the "supermassive" ones at the centers of galaxies have event horizons big enough to avoid death by Spaghettification(stretching to death).
Black holes are theoretically quite "easy" sources of "infinite" energy as you could accelerate things off them.
Worm holes are theoretically naturally occurring, just highly unstable without exotic matter
What you said about falling into a black hole and seeing the universe's end is theoretically 100% true and very impressive for someone not in the field!.
As for my own speculation, I'm more interested in the "hum" it's supposedly emitting, as that is (very) vaguely consistent with hawking radiation, especially with small sized black holes like this one would have to be.