I don't know for sure, but Michael Eisner worked for Paramount when they made films there and was studio chief at Disney when they made films for Touchstone.
So I suspect it was actually a case of their loyalty moved with Eisner. 100% guess on my part.
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'Days of London' - the 2012 Olympics, Days of Thunder style http://tinyurl.com/bbbkfxf
From Don Simpson'e Wiki entry:
In 1990, Simpson and Bruckheimer signed a five-year deal with Paramount worth a reported $300 million. However, the duo's first film for Paramount, 1990's Days of Thunder, received mixed reviews and while it was successful, grossing $158 million over a $60 million budget, the box office performance wasn't what the duo was expecting. Simpson and Bruckheimer blamed Paramount for the film's performance stating that Paramount rushed the planning and release of the film, while Paramount blamed the film's performance on Simpson and Bruckheimer's overspending. The duo mutually parted with Paramount shortly thereafter.share