That was my reaction too. Indeed, among the many possible ways to think about it, the sun can warm the compost heap, but not vice versa.
On the other hand, the sun is a cosmic compost heap. ;-)
On the other hand, the sun is a cosmic compost heap. ;-)
So, compared to any Earth-bound compost heap, each bit of the sun's surface (wherever you draw the boundary) has more heat-generating interior backing it up.