Any time anyone says it's a "slippery slope", you can freely disregard whatever else they have to say, because they're basically saying "I have no evidence at all but I'm going to try fearmongering about things anyway". If they had actual reasons, they argue based on those, instead. It's a phrase only used when they have no objective reason to honestly think things will go that way.
Your example, FWIW, wasn't even a slippery slope argument. Slippery slope arguments state that because events led to Event/Situation/Fact X, they will continue in that same vein to Event/Situation/Fact Y, which they frame as further down a certain path from X
It's a fallacy, because the only reason to go from X to Y is if there is a pressure towards Y. This was never shown, and a slippery slope argument assumes there is no such pressure, that we will "accidentally" slide from X to Y despite how awful Y objectively is. Not only is there an absence of evidence, the argument assumes that there is no evidence. It's not just bad logic, it's a way of saying "I have no evidence to back up my claims and no justification for whatever I'm saying."