Well, if YT is suppressing a user's video _because of their sexual orientation_, then yes, it would be.
If you have the option to send a letter, then your speech is not being suppressed. And if the telegram company is being considered a common carrier, your speech will not be suppressed.
All of these things (protected classes, common carriers, etc.) have already been considered.
Reverse it. Why do -I-, a private citizen or company, have an obligation to amplify your speech for you, often without compensation?
I don't.