Legal or not, it's the only way for such a law to have any effect.

Something similar happened over here in Europe (I believe it was in Germany?) where news media were allowed to demand payment from Google for being listed in their news sections/search results.

Google obviously decided to stop listing them, because there are plenty of news media that don't demand payment. As a result, the flow of visitors collapsed and the news media was very happy to go back to the way things were before.

I think forcing companies to pay for something and then taking away any control they have over that entire market sets a bad precedent. I don't know a better solution, but if this sticks we'll see other ways in which companies can be drained for money from basic internet services as well, only getting worse over time.

I imagine stock photo hosts demanding payment for memes posted on social media are waiting next in line. Imagine having to pay these platforms for your users' memes without being allowed to filter out the offending material. Stock photo companies could even start to artifically hype meme formats to get a bigger cut!