Jlobes, yes Im implying most of that but differently than your summary
-its not to be all rogue and crazy, its a microbiology take we can verify or discount.
The bacteria get myriad support we haven't considered, and you were implying is missing unless the keeper does X action, consider this but only as one of many self supporting pathways for the bac:
-do any animals on live rock respire vs photosynthesize? what is the waste product of aerobic respiration?
-are there any other bacteria on live rock that are not nitrifiers, or even marine bacteria at all? if they die in cycles, and deaminate in decay, whats the fuel that's leaked for the nitrifiers who are there right in proximity?
we do not digestion test live rock with living benthics unless burning them temporarily is the goal, and redundantly testing that which we already fully know (all bacteria present and ready) there are enough posts online of this type of redundancy, such that they will stand in for him burning his creatures above to be triply-redundant.
if he tests, his findings will be the same, always, so we offer to not burn the living verifiers and instead just make sure the current rock is leaking ammonia overcoming the nitrifiers, then treat it as if its a hundred years old and get going as one would from the verified systems we see routinely.
the reason you don't have to test group B rocks is covered in the link in great detail, and open to debate for sure, but its the fact that coralline and benthic life means the live rock is as good as it gets as a filter. true porous LR has football fields of surface area that stay covered in filtration bacteria whether its in high or low bioload tank, no portion goes sterile in the low bioload condition.