It was a very lefty kind of speech. He talked about “corporate vultures” ruining the US and demanding change.
UPDATE: Text of speech in block of this realclearpolitics article, but the video (below) is better.
PBS piece with video: https://www.pbs.org/newshour/politics/watch-teamsters-president-sean-obrien-speaks-at-republican-national-convention
From the article and speech:
“Remember, elites have no party. Elites have no nation,” he said. “Their loyalty is to the balance sheet and the stock price at the expense of the American worker.”
He added: “The Teamsters are not interested if you have a D, R or an I next to your name. We want to know one thing: What are you doing to help American workers?”
“Never forget, American workers own this nation. We are not renters. We are not tenants. Wut the corporate elite treat us like squatters, and that is a crime. We’ve got to fix it,” he said.
see also: https://www.axios.com/2024/07/16/teamsters-sean-obrien-trump-rnc-speech
O’Brien asked to speak and it was approved! My guess is: the party figured that Trump voters aren’t going to switch sides no matter who says what, but maybe they can attract a few from the center or left if they allowed a pro-Union speech.