the angels, willingly or not, already feed khorne when they succumb to the thirst. there are few beings in the galaxy that are so bloodthirsty without being a berzerker!! Of course Kabanda wants them alive!
So I guess what you're really saying is "this is awesome!", right?
I would be pretty disappointed if BA were turned after all the bullshit they've been through, all the while holding to their morals and defending the Imperium as best they could. The Sanguinor even showed up and bitch-slapped Dante when he succumbed to the Thirst and took it out on civilians once. That 10k+ years of resistance through constant hardship is a large part of what makes them appealing to me.