Confrontational has very negative connotations, it makes me think of someone always looking for a fight. Going head to head on an issue I feel strongly about or I think is unjust is something I'm prepared to do.
I am a bit suspicious that they felt the need to use that term in a person spec. It gives the impression that they are having problems with staff at each other's throats. Or they just want someone who will put up and shut up.
We have met the enemy and he is us.