For me, much of the poignance of the scene came only in retrospect. As I was first watching the episode, I was far too tense and worried for Tilly to truly appreciate not only how appropriate that song was to the situation but how the entire sequence spoke volumes about the depth of her and Paul's relationship. I admit I don't know Bowie as much as I should but I agree that he'd definitely be among those who withstand the test of time and the more I think about it, the more sense it makes for Tilly finding his music close to her heart.
It got me the first time, but definitely more the second time. I suppose I'm hoping it was the original version she was fond of

I wonder if this bit, plus Reno's reference to Prince was scripted, or if they let them adlib. I could see it with Tig, her smart-ass-ness is front and center. Glad they kept her on board.