Michael Bearden, who was previously the keyboard player and musical director for "This Is It", was the conductor of the orchestra. Makes sense that he would throw in a snippet of an MJ song.
Also, having "Ease On Down The Road" be the tribute song for Quincy doesn't make much sense when you think about it. He didn't write that song for the original Broadway musical. I guess you could make the argument that choosing a song from "The Wiz" makes sense since "Wicked" was nominated for a bunch of Oscars this year, and both are movies based on Broadway adaptations of the Wizard Of Oz. And technically, Queen Latifah DID play The Wiz in the 2015 Live version.