Stronger?

Tuesday Mary J Blige's video for "stronger" hit the air waves. One thing missing was the lead vocals from Chris Brown. The final project has Chris' background vocal and will appear on Lebron James' upcoming documentary.
Mary J was ask who's featured on her upcoming Stronger album. She mention Drake and TI . No mention of Chris Brown did Mary obmit him cause of the Chris and Rihanna saga? Maybe Mary's people and Chris' people couldn't agree on the usage of the track.