I think you are failing to understand the rules of logic. While what you say is true about there being differences, it doesn't change the fact that the slippery slope argument was not used fallaciously in this case. There are no steps to get to between A and B, we need make no new assumptions to get there. Therefore, this isn't a fallacious use of the slippery slope. That doesn't mean there aren't any valid rebuttals to the argument; it just means the argument was not fallacious. An argument doesn't have to be fallacious to be incorrect, and that is what you are truly arguing here.