Most of her fans are probably listening to this album via Spotify or Apple Music on bluetooth headphones, right? So whatever is at 15 Khz… they’re either gonna think it’s part of the experience or not going to hear it anyway, because it’s been filtered out by the compression.
Why would it be a waste? If something is mastered with 24 bit (and has a theoretical dynamic range of 144 dB) surely something has to be lost if you resample that to 16 bit and a 96 dB DR?