But they are misusing it. There are articles besides the 19th.
Tweeting content disagreeable with Twitter, Inc. cannot be a right under the UDHR because of Article 20.
Article 20
1. Everyone has the right to freedom of peaceful assembly and association.
2. No one may be compelled to belong to an association.
"An association" doesn't mean an organized body like a club, political party, or union. It means any tangible or intangible connection of any type between two parties.
The twin freedoms of speech and association means a newspaper can't be forced (in civilized countries) to publish content against their will. The owners of the paper can't be forced into an association with ideas or speech that is not their own.
Same goes for Twitter. If Twitter wants to delete or prevent the dissemination of any tweet for any reason at any time-- that's their right.
If this was not true, then my local newspaper would be violating my rights for not publishing my letters to the editor. Are they?