For a slippery slope there has to be something about the slope that makes you start at the top. If you can go to any point on the slope, it isn't even a slope.
Anthropic can start censoring criticism of Dario completely independently from whether or not they censor Deepseek.
If the slope is slippery, it is not a fallacy to conclude that things will slide when placed on it.
Claiming something is a fallacy —when it is not— is simply a false statement of fact.