Via Nathaniel Grow (who teaches Legal Studies in the business school at Georgia): The image at left (click to enlarge) is a page from the October issue of Yankees Magazine and features the team's ticket policy. Note the underlined language in the inset at the top--fans acknowledge that team policies banning foul/abusive language and obscene/indecent clothing do not violate their free speech rights and they waive any free-speech objections to those policies or their enforcement.
I find it interesting that the team is now framing its attempts to regulate fan expression explicitly in free-speech terms. It suggests their recognition of my core argument--that fan expression, even profane or objectionable fan expression, is subject to First Amendment protection and analysis. This policy is an effort to wiggle away from that legal reality. Of course, the idea of "acknowledg[ing]] and agree[ing]" that something does not violate one's rights when it probably does is pretty Orwellian. It goes well beyond a waiver of a claim into a compelled agreement to an alternate reality.
More fundamentally, even as a straight waiver, it cannot possible be enforceable. Assume for the moment the Yankees are a state actor in managing the ballpark--I argued they were with respect to the old Yankee Stadium, which was owned by the City of New York, although the analysis changes for the new ballpark, which is privately owned but (largely) publicly built. The government cannot condition access to a public forum on a person waiving their right to challenge constitutionally suspect limitations on their speech in that forum (imagine a parade permit saying "As a condition of accepting this permit, you agree that police can halt the parade if your speech is objectionable"). Nor is this saved by the fan's compelled acknowledgement that "such time, place and manner of [sic] the restrictions are reasonable." While it is telling that the team is using those precise words, a TPM restriction must be content-neutral; a ban on foul language and indecent clothing is so obviously not content-neutral.
Finally, I do note that the waiver only applies to dirty words and dirty clothes and not to other possible free-speech violations, such as compelling fans to remain standing by their seats for "God Bless America" or other forced patriotism. I wonder if that is an oversight or if the team has genuinely given up on those efforts.