MAD ammeter bypass question

No I understood that. The MAD recommendation is 14 ga fusible link by the way. It does prove how fusible links provide little protection except from total disaster which is what I think the original design intended. With a short don't you think that you are going to melt something whether it is a connector or a wire before the fusible link goes anyway?
Yes. The purpose of the fusible link is to protect from a Battery short to ground while providing sufficient current carrying capacity to avoid resistance levels that will result in noticible voltage drops during normal operations.