I don't understand your objection. If tool A says "job is done" and tool B says "found N additional tasks that need doing" how does the history matter? B is turning up things that A isn't thus B is performing better. They both had access to the same inputs here.

I suppose it's interesting to wonder if B would have turned up issue X which A previously found. But that seems largely academic to me. There is a code base right now with N known issues (thanks to B) and A is saying everything is good. It seems like that's all that should matter here.