Yeah, its not that science doesn't play a role, its what the Bottleneck is.
ie you will need to have some science, but it is not a race to then end of the tech tree like the space race (you might have to get to the outer ring, but that is pretty easy)
I think they aren't science victories as much as the steps involved would most resemble a CivV science victory
1. get certain techs (but you don't need to finish off the tech tree for the BE victories)
2. Build certain things throughout your empire (first the big wonder, and then pour production into it..either directly, or by building units)
That explains the Contact, Supremacy, and Harmony victories
The Purity Victory might be a little more militaristic as you have to have a certain amount of territory to win.