It’s a sign of trouble, but I’m not sure it’s really “further” trouble, all it takes is for them to get a cert from Let’s Encrypt and call it a day. I’m surprised they weren’t using LE to begin with actually - since LE is available, why would you ever pay for another CA (excluding EV certificates)?
This is a much bigger deal than people are giving it credit for. At any point in history, have CAs revoked certs solely to censor a target website? Maybe the answer is yes. I don't know. But this is a rude wake-up call for me and everyone else who tried to force the world into this shape. We've all been shouting "You have to use TLS! It's fundamental security 101. If you're not using https, your site is probably brok…
Really the issue is that decentralization isn't very compatible with convenience and people generally place a lot more value on convenience than things like Sci-Hub.