Everyone who cares even a little about their academic career. Apple doesn't really let you publish. Even pop-sci articles they do publish on their website don't have any names. I know no sane researcher who would agree to end their academic participation so abruptly, particularly in order to work for an organization widely perceived as a perennial laggard.
But... they didn't. In the very page you linked, try to find a single name of a concrete researcher who wrote/contributed to the article. If there's no name on the paper it's not "publishing".
Learning from Simulated and Unsupervised Images through Adversarial Training by Ashish Shrivastava, Tomas Pfister, Oncel Tuzel, Joshua Susskind, Wenda Wang, & Russell Webb.
How about both. Google, Microsoft, and Facebook both pay their researchers very well and let them publish extensively. That's why they have world-leading research organizations, and Apple does not.
Do you have evidence that Apple pays AI researchers less than those other companies? Honestly I'm not sure that you even understand the argument you're trying to make. The rest of us here certainly don't.