Some large asteroids have moons too.
Some large asteroids have moons too.
Assuming your math is correct (and I have no reason to doubt that it is) a mass of 10^16 kg would actually be a pretty small moon or moderately sized asteroid. That’s actually roughly the mass of Mars’ moon Phobos (which is the 75th largest planetary moon in the Solar System).
no no, the end user will somehow find the exact position in which the switch starts arcing and then they’ll work by the light of the fire in their walls.
There is no clear definition of what constitutes a moon other than it being a body that orbits another body that orbits the parent star.
There are some astronomers who say the dividing line between a moon-planet/dwarf planet/asteroid system and binary (or more) planet/dwarf planet/asteroid system is whether or not the barycenter of the orbits is within one of the bodies or not.
And fun fact: if that definition gained acceptance, it would mean that the Pluto-Charon system would go from a dwarf planet-moon system to a binary dwarf planet system. Charon could get a promotion.