It's like walking into the mall or public place, and saying, "You have to broadcast this message to everyone because 'freedom of speech'"".
In fact it's better to assume that private companies have such ability anywhere in the world. Signal fosters more access to defy censorship precisely because it realizes that. Making the software open source is how you allow people who need such tools to have them available.
And honestly... you've got the airwaves. It's called radio. Shortwave, can reach halfway around the world.
Again, the entitlement to these services astounds me. The internet didn't exist 40 years ago.... and now somehow the ability to assault people with misinformation, provide unfettered access for propaganda from state actors, permit the dissemination of hate speech is being called a right??
It makes no sense, and is completely devoid of historical perspective.