Slippery slope is vastly oversold as a logical fallacy. It is only a fallacy in the absence of evidence that there is a slope. If there's a multi-decade trend of which this is only a single step, and there's no visible mechanism for making it stop here and go no farther, then the logical fallacy is in believing with no reason that the trend line will stop here.
It is not a fallacy to speak as if this is only the beginning of a huge push into intrusive monitoring. It is a fallacy to pretend otherwise.
Slippery slope is also a fallacy if you take one instance of a trend and then logically project it to an absurd extreme, but this is not what we're doing here. We're simply looking at the next obvious, logical, well-evidenced step, with plenty of people who obviously want this even if they are a bit too discreet to come right out and say it in public.
But it's not a hard leap to see that our rulers today would like to be in full control of everything bit of data we receive and every bit of data we produce and the only things stopping them are technical possibilities and whether or not we'd put up with it. I see nothing else stopping them; not scruples, not morality, no existential awareness of the sheer staggering amount of responsibility they would be pushing on to themselves, no concerns about how it may hurt anyone, nothing.