The fact that there was hate speech by a user, in this case the President, means that Twitter acted in support of its broader platform. It has no obligation to the President or to support his preferred communication platform for hate speech.
I don’t think the state has the Constitutional power to compel private parties to relay what officials say outside of exceptional cases, because of freedom of speech and the press.
The right to hear isn’t the right to commandeer others resources to have it relayed to your hearing.
One of those should be to refrain from using their power as a transmitter of information to manipulate the relationship between the people and their government. Maybe here, they have some noble purpose, do we trust that in the future they always will? Maybe in the future they would delete the accounts of Senators who call for antitrust investigations into Twitter. Who knows? Once they have the power, do you trust them to use it only for things you agree with?
A right to hear without any mechanism to enforce it is pointless.
We place reasonable restrictions on companies that serve the general public to ensure they treat all members of the public fairly. You can't decide not to serve certain customers because you don't like their skin color or religion, for example. Another reasonable requirement for a communications company would be that they accurately relay the communications that their users send, without interfering with or manipulating them to serve the company's own purposes.