So there are two general objections here.
1. "This cuts into FFG's profits.": It probably does, but as a customer, I would not care about this if I were you. We are not playing this game to keep a company alive, just as they are not selling the game to make our spare time more fun. But the point is rather moot, since 3rd party dice should not cut too deep into FFG's profits.
2. "These dice cannot be trusted.": Welcome to the world of RPGs, where everyone uses dice from different manufacturers. None of the dice at a typical gaming table have ever been tested. Many are actually slightly skewed. We don't mind because we don't know.
If someone wants to win so desperately that he will bring loaded dice to a casual game, or manipulating them, I'd be more than happy to just concede before wasting both our time by actually playing. After all, if the outcome is already known, why not just cut out the middle bit?