This doesn't make much sense when you think about the context of the original work you're quoting.
Niemoller was writing about a fascist government. Fascism is inherently built on an "us-vs-them" conflict. The details may change, but a key point is there's always an enemy who is responsible for everything that's wrong with the world. When fascists take power, they set out to get rid of the enemy. Then they find that didn't actually fix anything, so they splinter away some of their former in-group and make them the new enemy.
That is what fascists groups in power must do, because of course everything is much more complex than they claim. Nothing is ever as simple as "if we get rid of that group of undesirables, everything will be great", no matter who those undesirables are. Socialists? Capitalists? People who post on HN? Any other group you might name? The answer is never as easy as "those people are bad."
There doesn't need to be a slippery slope from whatever the government wants to outlaw to everyone being a criminal. It depends on the structure and goals of the government. In a fascist state, yeah it's pretty much guaranteed. In the US? Well, we're a muddled mix of everything with a very mixed record and uncertain future, but at least we're not a fascist state. There isn't a guarantee that any step leads to a next step.
So it really isn't analogous to the situation the original work was describing. And it's not really constructive to weaken its point by making jokes applying it to this situation, given the point it's trying to make. But maybe the fact that so many people don't understand the context means it's already too late.