I know President Obama and Hillary Clinton and Nancy Pelosi have also done these, and they've been pretty meaningful spots. I think it's good when people lend their voices to an issue in solidarity with any out group--it means something to know that it isn't an issue that just affects LGBT folks, but impacts everybody. But I think how Trumka relates anti-gay rhetoric and bullying to the variety of ethnic name-calling and the real-world penalties that people can face for being different in the workplace as well, bring up important points.
(Side note: I'm big on unions because of the issue of workers' rights, and the need for genuine cause in firings. I hate that orientation can still be an issue for one's employment security. I think that should be every bit as big an issue as marriage equality and the end of DADT. If there is a form of DADT in workplaces around the country, that's a cause for real concern with the economy being what it is. Especially since at least the military isn't supposed to ask. But that isn't exactly the case everywhere else.)