Nah, they pretty much force you into taking the reclusive, "don't stir up the people" kinda role.
Don't they also have you kill important people in cities to frame the Dawnguard and turn other people inside cities into Vampires?
Well now we get into the definition of evil and all that. Their first priority is to feed. If an opportunity came up where they could make it easier for themselves...
Feeding isn't an issue. They get you while you're asleep. Though they're careful, and have rules about it. They can't truly hide from Mages, chances are many probably strike deals like Janus Hassildor did.
All that page shows me is that Elisif court is either very incompetent or lack of any common intelligence to realize who Sybille Stentor truly is.
Sight... Perhaps the Aldmeri Dominion is our best option for Tamriel after all.
It isn't easy spotting a Vampire if you're not a Mage, or trained Vampire Hunter.
Then many Stormcloak Jarls are incompetent too, since I've had to slay many "Advisors" who were Vampires. They even plan to turn the entire Court and Jarl into Vampires, and you get a bounty if you simply kill them.
I guess Nords simply lack common intelligence? Leave the ruling to the Empire, it seems us Imperials have to do everything... Gold star for effort though. It looks like we need to have the Legion take over, the Nords just aren't ready to rule without us holding their hand.