I disagree. I think they would pick the highest finishers from Group 3 in this instance, given that both Mariah and Karen are quite inconsistent themselves. Karen has already been picked ahead of a higher finisher once, so I can't see the USFSA doing that two years in a row (especially if Karen finishes off the podium).
I think that getting saved by the selection committee should be a one-shot deal, you never get that lifeline again. And while Karen and Mariah have their own inconsistency issues, they get better PCS than Amber.