Earlier quoted context omitted.
Nobody is forcing Trump to use Twitter. They are saying that if he uses Twitter, he must leave his tweets open to all the public and not a subset. President Trump could always choose to close his account if he finds this requirement to be too onerous.
Do his Gmail emails need to be open to all the public? His Slack messages? His Facebook posts? I don't see how anyone, president or otherwise, can't chose whom they send messages to.
If they are being used to conduct official business, most likely yes. They will need to comply with federal regulations for data retention, public disclosure (or confidentiality as the case may be), etc.
You may recall another candidate who was running for president in 2016 getting raked under the coals for using personal email to conduct federal business.
> I don't see how anyone, president or otherwise, can't chose whom they send messages to.
What's to not understand? They are acting in an official capacity. Thus they are legally and ethically bound to a higher standard.