Vanilla is a product of Lussumo:
Documentation and Support.
and if the victim said no, that they wanted to keep their memories then Sirrka would be forced to mind wipe them a little anyway to erase the questioning...but...that's a smaller sin I believe...
They let Alice keep HER memories -- why? What makes memories of Mark implanting "command lines" in her head and sending her off to murder people such a beneficial thing to remember? Why was Alice "let in"?