It’s bizarre. Even if Roon makes an incorrect association of The Stills with Stephen Stills of CSN/Y. At least there shouldn’t be only tracks from Deja Vu. There’s a lot more material to choose from CSN, CSNY, Stephen Stills solo, Stills-Young band and other similar artists.
I find the same problem with Daily Mixes as I find with Roon radio. Highly repetitive from an artist selection point of view.