It'd be an easy out for Dexter, to a degree, but it would make sense, given what we know about Quinn so far. At the very least, it would make a red herring.
We already know he's crooked from last season. He's always been a little skeevy, which has been emphasized in this week's ep.
Before Lumen's rapist was caught on the phone, Dexter was trying to cast doubt by pointing out that the guy was a dentist and family man--a good guy--only to find out Lumen's accusation was true. Meanwhile, Batista is telling Deb that Quinn's a "good guy."
It's possible, and it wouldn't be from left field. In fact, you can pretty much bet that someone we know is involved, whether it's Quinn, Weller, etc. Heck, that's probably who the rapist called to warn.