These sites believe that they face an existential crisis due to this proposed legislation. Slightly impacting the service today to save it for the long term is clearly worth the tradeoff, if it's necessary.
Well, I guess a number of people disagree with me. And I can accept that (although I still disagree). But I think I should point out that "worth the tradeoff" is not the issue I'm talking about. For example, suppose I pay for something at a store, but the store refuses to give it to me, because they're protesting something. We can certainly ask whether the store's policy is "worth the tradeoff", but is that really the question we should be asking?
But that's not at all like the situation at hand. They're not refusing anything — it's only for one day, and if you don't want to participate, you don't have to. What you are complaining about is a minor inconvenience at worst.
They're not protesting "something". They're protesting a law which they believe has a good chance of passing, and which will likely put them out of business if passed.
Now, should they interfere with your paid service because of that? I don't know. But it's not cut and dried either way. The best would be for the law to go away and for your service to continue without interruption. But it doesn't look like that's possible at the moment. You have to choose one, and neither one is something they "should" do.