there were lots of tracks on the boxset that were incomplete early versions, demos etc...
wonder if there's a more valid reason, like lack of a decent master tape?
I'm with Brenski. But I think they might have included it anyway, considering that the source of the track sounds like a homemade taped demo. They included those Barcelona homemade sessions, or Lady with a Tenor Sax, which sounds a bit like low quality (from the beginning till the minute 3:13). And there is free space on the CDs to put like three or four more songs, and is more worth to listen than songs like God is Heavy (which they included to hear Freddie with a cold), Horns of Doom or Yellow Breezes.
Anyway, this Box Set is absolute great and it seems to be made with a lot of effort and "love". They really attended Freddie's fans with this one. Let's pray to have one like this from Queen when the 50th anniversary comes.
I didn't know it was recorded during the A Kind of Magic sessions - I have always thought it were a solo song. A shame it wasn't finished!
Thank you all for the great answers.