There is some misconception on your part about the location of some of the contaminants of concern. To my knowledge, mercury is not distributed differentially in fish. Likewise, the fatty tissue is not distributed only in fish guts and darn none in fish heads.
The other issue you seem to have missed is that of sensitive populations. It seems to me that your perspective is from that of the average sports fisherman can obviously consume more than someone who is immunologically challenged or the young or old. You should consider boning up on caring for the rest of the population :>) The cost of your being wrong is of much more consequence to fish eaters than if the advisory is wrong.