The article is from a UK newspaper. What is and isn't legal for them to regulate is decided by their Parliament and nobody else. No Kings, and all that.

Meanwhile, you should know that the "free speech" lectures are getting pretty old from the country that checks social media history at the border to make sure you didn't say anything bad about the Dear Leader, which shuts down TV shows it doesn't like, and generally ensures the media toes the party line.

(See also - lectures on why kids shooting up schools is a necessary price to pay for that well regulated militia that will be along to save you from tyrants, well, real soon now...)

Go yell "fire" in a crowded theater, or "i have a bomb" on an airplane and see just how quickly the government regulates your speech.