Michael Eavis is a fan of Neil Young is he not? Pure speculation on my part but he might not have too many more festivals left and maybe that influenced the booking? They clearly like to have a legacy act playing and with it looking like O Rod & The 1975 maybe NY made sense if they couldn't get stevie wonder for example.
Also spotify stats for artists like him are close to irrelevant. By in large, the bookers know who is big enough and the only exception to that is when they have to scramble for a last minute headliner