David Bowie was on the cusp of superstardom in the spring of 1972 when he decided to donate a Top 40 song. He’d already released two U.K. Top 10 singles in the spring of 1972, including the chart-topping “Space Oddity.” Bowie’s 1971 album Hunky Dory had been a platinum-selling No. 3 smash in his home country. More importantly, he was just completing the career-defining The Rise and Fall of Ziggy Stardust and the Spiders From Mars, which would finally break Bowie in the States. That’s a moment when few would bother worrying about anyone else’s fortunes, but Bowie suddenly became very concerned …