This is a good point.
What if there wasn't a tradition of sending the top finishers at nationals and the committee still went with Flatt because of her consistency or because they wanted to send Nagasu a message that they aren't going to bail her out if she continues to freak out in the free skate? Both would be legitimate reasons to pick Flatt over Nagasu and yet if it happened you'd hear cries that Zakrajsek used voodoo on the committee to get Flatt a spot.
And if they chose Mirai you'd most definitely hear the same thing about Frank. Come to think about it, it might be fun to watch Frank Carrol make a huge stink if any of his skaters are ever past over by some committee.
In any case, I do think that in this case even most posters agree that Mirai doesn't have nearly the history to justify bumping a solid skater like Rachael. But just trying to throw examples out there and make a point...