I am not too sure what qualifies as being feminist or not. I mean making certain statements to please women or others to anger anti-feminists does not make you a feminist. Also, walking out on the streets with pickets in your hand to demonstrate at certain causes also does not mean that this is the only way to be a feminist. I am a stay at home mom with two children, and I am a feminist. With people in the entertainment business who make money with "feminist" songs, etc., I am sure there is a business/marketing element involved.
Having said all the above, I don't know Beyonce's work enough to make an educated reply.