>>150094503
Well because the Roche Limit is for accretion. Death Battle's argument would only work if the bodies started off in a sphere and were pulled into orbit to form the disk.
Likewise part of their argument is built on the assumption that such a disk would only exist for the time in orbit if it was stable. But that's not true, the amount of time that the graveyard orbit could sustain this amount of space trash extends into the 5k or longer range.
I'll not pursue the topic of the moons since those objects could honestly be anything and it just isn't very consistent across depictions.