Atlanta airport WiFi users are barred from transmitting "hateful or racially, ethnically or otherwise objectionable" material

That's part of the Atlanta international airport's Wi-Fi System Acceptable Use Policy, which travelers must agree to in order to access the system. A slightly longer quote:

The following constitutes examples of violations of this AUP. You agree NOT to use the Wi-Fi System to:

Transmit any material (by uploading, posting, email or otherwise) that is unlawful, threatening, abusive, harassing, tortuous, defamatory, obscene, libelous, invasive of another's privacy, hateful or racially, ethnically or otherwise objectionable; …

Impersonate any person or entity or falsely state or otherwise misrepresent your affiliation with a person or entity; forge headers or otherwise manipulate identifiers in order to disguise the origin or any material transmitted through the Wi-Fi System; …

Transmit any material (by uploading, posting, email or otherwise) any unsolicited or unauthorized advertising, promotional materials, "junk mail," "spam," "chain letters," "pyramid schemes" or any other form of solicitation …

Resell the Wi-Fi System;

Use the Wi-Fi System for high volume data transfers, especially sustained high volume data transfers, hosting a web server, IRC server, or any other server.

This is pretty clearly unconstitutional. The WiFi system is either a "designated public forum," which is to say a facility for speech that's opened up by the government for use by speakers generally, or a "limited public forum," a facility opened up for speech by certain speakers on certain topics. A "public forum" need not consist of physical space (such as a room or a park), but may include any subsidy program through which the government facilitates a wide range of private speech, such as the printing fees reimbursement program involved in Rosenberger v. Rector (1995). But even if it isn't a designated or limited public forum, but is merely a nonpublic forum, in any case viewpoint-based restrictions on speech in such programs are unconstitutional. (See, e.g., Rosenberger v. Rector (1995).) And a restriction on "hateful or racially, ethnically or otherwise objectionable" discriminates against speech based on viewpoint (and the "otherwise objectionable" provision is likely also unconstitutionally vague).

To be sure, the government is under no obligation to provide such WiFi services (though I take it that there's a good business reason that many public airports are providing the services, to customers who are indirectly earning millions of dollars for the city). But once it provides the services, it can't exclude speech from the services based on viewpoint. And while this language seems to be boilerplate borrowed from somewhere by some low-level employee, and not a deliberate high-level decision to bar certain kinds of speech on the WiFi network, that doesn't make it any more permissible. Enterprising Atlanta law students who are looking for a fun project might want to check this out.

UPDATE: I've beefed up the "public forum" paragraph, though the bottom-line point—that viewpoint discrimination is forbidden in this program—remains the same.