I don't think Vivienne will care. She's not pro-Chantry, she's just pro-Vivienne.
For all we know, she IS a blood mage.
let me consult my DA:II character development.
Q1 is the character a mage? Yes go to Q2 No go to Q3.
Q2 is the character weak or strong? Weak A1 Strong A2
Q3 Does this Character generally hate mages? Yes A3 No A4
A1 this pathetic mage is pitifully weak, Absolutely has to be made tranquil to stop it turning to blood magic. typical for mage scum this character has refused to accept what is right and in desperation has turned to blood magic, slay them before they become a dangerous Abomination.
A2 this character is a Dangerous Maleficar its true strength and hubris lies in its secret knowledge of blood magic, kill it before it brings forth legions of demons and twists the minds of other beings
A3 Congratulations this character is pure and righteous ready to rid the world of evil blood mages, place them in the highest available office
A4 sadly this poor mortals mind has been enslaved by an evil Maleficar, you should kill it immediately to send a message to its puppet master that we will not tolerate blood mages.
By DA:II standards Vivenne is most certainly a blood mage.