I've been pondering my original swing at this subject.
Range Masters must consider the ramifications of their decisions across the board, not just in a specific incident.
My original thought was going minor is a scoring issue, and nothing else. If shooter a benefits in anyway from the RM's decision, it is most likely at the expense of another shooter. That is why these things are important. This brings us to the question of is having your scores re-calculated to minor outweighed by the ability to load one or two extra rounds. As has been discussed already it depends a lot on when you find out you went minor.
Honestly, it's a tough call. Because I might be faced with this scenario in the future, I would like to get it right.
I belong to an RM discussion group, and even though we seldom are unanimous on anything, I'll bounce this off of them.