Filter.
The HPD knows about what I saw last night because I told them. I didn't know what it was, and they've put two and two together. Right now, the puppet spell is keeping you from killing anyone. I don't know how well it'll keep you from hurting someone, causing traffic fatalities, property damage, etc etc.
I'm making the offer because I know how the supernatural world gives out bum deals. It wasn't your fault you were attacked and turned into this thing, and if I can make sure you're safe for yourself and other people while the eggheads figure out how to turn you not-scaly, then that's something I want to do. It's what I do back home, anyway.