Yeah, as I was writing it I thought the same thing. If not density though, then what do you measure as the… object itself? Since the prevailing theories are that black holes are either infinitely dense in a singularity, or that some are gravistars, we’d either turn an infinitely small dot into poop, or we’d turn something large enough for the poop to be dense enough anyway, so it may just shrink the blackhole.

Second point also works if using Schwarzschild radius or Kerr metric instead of a gravistar.