To do this type of business legally, you have to comply with both federal laws and state laws. The federal laws basically say you have to register with FinCEN and comply with anti-money laundering laws, which mostly means you have a duty to know who your customers are and why they're transacting with you, to refuse to do business with people who are obviously laundering money, and to report suspicious activity to FinCEN. It's reasonably doable to comply with federal law as an small operator. However, this person didn't just fail to register, she also knowingly facilitated money laundering, which is illegal even if you're registered.
What exactly you have to do to comply with state law varies dramatically. In some states buying and selling bitcoin is basically unregulated, and in others there are onerous registration/licensing and financial requirements that are basically impossible to fulfill as an individual. Off the top of my head I'm not sure where California falls on the spectrum.