In the example in from that what if, they are putting a universe's worth of mass in the volume of the moon, so it would create a super massive singularity. That's not what is happening in here.

Not quite, xkcd put a moons worth (by mass) of electrons together, so if we add an electron to each atom we go down four to five orders of magnitude.
The black hole came about, because the electric charge creates a electric field in which the electrons have a potential energy that by E=mc^2 is equal to the mass of the universe. If we apply our scaling factor we still end up with black holes everywhere.

Lets play with those numbers:
Scale factor between Sagittarius A* and the observable universe 10^37 / 10^53 = 10^-16
Mass of Moon 10^23
Mass of electron cloud equivalent to black hole 10^23 * 10^-16 = 10^13
mass of electron added object equivalent to black hole 10^13 * 10^5 = 10^18
That means adding an electron to each atom is enough to rival the black hole at the center of the Milky Way. Even if I miscalculated by many orders of magnitude, at least each planet collapses into one.