After watching
I'm pretty sure its not sexual abuse at all. In fact, the Sith Warrior actually enjoys torturing lesser beings for fun and not as a sexual thrill. Maybe you're just looking at it differently, and with a far sicker mind.
By the way, you can't romance Vette while she still has a shock collar on. I have a 50 juggernaut and, while I did remove the collar once I got off Korriban, I find nothing sexual about shocking her. Vette will sometimes say witty remarks after being shocked, but for the most part in that video she expressed pain and usually asked him to stop (sometimes screamed at the warrior).
As far and equality for all species and genders in the Empire, theres no such thing. To the sith, humans and purebloods are the more powerful species and are looked upon highly. Aliens are lesser beings to the sith. As far as genders go, Twi'lek females are usually dancers and males are usually workers, building momuments are structures. (Twi'lek being an example.)
Just the way I look at it, is, Vette is similar to Eleena Daru, Darth Malgus's slave lover. Darth Malgus treated Eleena has an equal and loved her, even though she was his slave. Though Malgus did kill Eleena at the sacking of the Jedi Temple (the trailer that I forgot the name too) for saying his real name, Veradun. Also he said that she was his greatest weakness. (He was extremely aggressive towards Jedi Master Ven Zallo who had deflected a blaster shot back at Eleena and pushed her to a pillar.) Although after he killed her, he regreted it which fueled his passion and hatred.
You can keep Vette as a slave and shock her as much as you want or even just not use her OR you can remove the collar and produce a friendship between the two of you.
Just my thoughts.