So after a bit of thought, I think I know why Scarlip referred to Lindsey as a threat, despite being just old enough to drive a car. It's not what powers may/may not/obviously-don't-since-the-Dave's-already-said-she-has-no-powers, but it DOES have to do with what she's done. More, it's what she represents:
Hope. If the Bloodwatch let it be known that a girl, a teenage, emotion-reacting-ponytailed little girl led a small, but obviously irritating revolt against them, then their sheep would realize THEY can rebel, too. Not just the "One Tree Hill" watching, boy-crazy, secret-thong-or-their-parents-would-kill-them girl crowd, but the big burly and really intelligent folk that aren't in their hypnotic sway. They, too, would rise against them throwing further monkey wreches in their plans.
Henchmen can be replaced. But secrecy? That's a little harder.
...Geez, why'd I use so many hyphons?
