The reason cited for his departure was creative differences with the remaining members of the band Queen. They have full script and director approval, and were not seeing eye to eye with Sacha Baron Cohen in terms of what he wanted to accomplish with this musical based drama.
Queen was in the market to make a PG rated film that would appeal to families. Sacha Baron Cohen, known for his raunchy comedies, wanted to do a gritty hard-R take on the singer's homosexual lifestyle.
The film is at Sony. It is unclear what will become of this project at this time.