Nah, I'd say it was more just the idea of what he's done that caused the turn, and the fact that, as we've learned, he's polish - Anyone from that nation would, by and large, be disgusted and horrified at the idea of genocide.
More to the point, it's more than a little different than what he's done with Tomorrow Woman - Again, a character deliberately designed as a villain, so to have him be a stooge, I think, takes away from the impact and power of Morrow admitting what he's done.