Simpler better solutions:
1. Just ban Finn from phase 2 and 3 of the raid.
2. Stacking tenacity on traya (could even limit this to 'when attacked by a resistance enemy)
3. Reduce TM gained by Finn lead against raid bosses.
I don't even have the zeta but think it's ludicrous not to offer the refund to people. It was probably not a good move for people to put the zeta on him just for HSTR, but even those people should be excused for thinking the zeta would still be the same outside the raid. For everyone else you are making a material change to a significant investment.
