He was, he played the harpsichord on "Angel in my Heart" at least.
But something did happen for WS because I remember flipping through "Vanity Fair" in early 92 with Mick on the cover and he was interviewed during studio sessions with Matt Clifford, dubbed his "musical aide de camp" in the article, for "Don't Tear Me Up". It seems the results of these first sessions for WS were not to the liking of Ahmet Ertegun (according to French journalist Philippe Manoeuvre's review of WS) and he told Jagger to rework it. That's possibly when he went to Rubin and ditched the previous sessions with Matt Clifford.
There might have been some tense moments at that time with Clifford, hence Chuck's revelation in his book that Mick was looking for another keyboard player to replace him when they regrouped for VL...
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IORR Links : Essential Studio Outtakes CDs : Audio - History of Rarest Outtakes : Audio