Yesterday, Nextdoor CEO Nirav Tolia was charged with a felony for allegedly leaving the scene of a hit-and-run that left a female driver injured. Speeding away in a BMW X5 reflects poorly on a startup like Nextdoor, which raised $100 million to build a social network for good neighbors. But for Tolia, this sudden scrutiny could also undo years of rehab on his tarnished personal brand.