Honestly I don't see why everyone thinks this is so crazy... Sure, adjusting the blades right after the warmup is highly unusual. "Crazy" implies that he shouldn't have done such a thing, though. From my perspective though, it seems like Shoma simply had a problem he needed to solve and he finally solved it...although he only figured it out during the 6-minute warmup.

Sometimes one can get so stuck on certain aspects of a problem that the solution appears only when one least expects it...
Hope you have a wonderful time at the Grand Prix Final!