Whilst this is hilarious, it does pose a question as to whether or not non-physical locations can be declared public forums. The definition of a public forum is as follows:
In United States constitutional law, a public forum is a government-owned property that is open to public expression and assembly. A public forum, also called an open forum, is open to all expression that is protected under the First Amendment. Streets, parks, and sidewalks are considered open to public discourse by tradition and are designated as traditional public forums. The government creates a designated public forum when it intentionally opens a nontraditional forum for public discourse.
There are a few different things that need to be considered.
- Is Trump's Twitter account technically "government property", does it belong to him personally or does Twitter own it?
A note on this. The White House Press Secretary released a statement that Trump's tweets are considered as official statements from the POTUS. If users are banned by Trump, they can not see/comment on these statements.
- Do public forum laws apply to non-physical spaces?
I did find a case similar to this in which first amendment arguments were used:
The 1988 decision in Hazelwood v. Kuhlmeier relied on the notion of a public forum in determining the degree to which a public school newspaper that has not been determined as such a forum can be protected by the First Amendment. The Court decided that such newspapers are subject to a lower level of First Amendment protection than independent student newspapers established (by policy or practice) as forums for student expression.
- Can Trump block users anyway, citing their use of language or manner as a reason for them to be blocked?
First amendment rights do not extend to things such as violent protests. However, exclusion based on the speaker's viewpoint can be deemed unconstitutional.
In the 1972 case Grayned v. City of Rockford, the Supreme Court found that "The nature of a place, the pattern of its normal activities, dictate the kinds of regulations of time, place, and manner that are reasonable." In determining what is reasonable, the Court stated that "[the] crucial question is whether the manner of expression is basically incompatible with the normal activity of a particular place at a particular time." Thus, protesters have the right to march in support of a cause, but not on a public beach during the middle of the day with bullhorns.
Does this mean that if Trump's Twitter is indeed a public forum, he could block users based on the content of their tweets to him, particularly if they went against Twitter's terms of service?
Public commodity more like. Popcorn prices have gone up three fold since inauguration.