Hey, in California, the government authorities are always looking for a reason to raise taxes. Making up the difference in legal fees might just be another way of skimming additional revenue.
I see this as more a response to being unable to raise taxes. We have laws against prostitution which require money to enforce. We have much bigger problems that are more deserving of what law enforcement dollars exist. So how to enforce this law without spending money on it? Try to chill it. It's cheaper than enforcement and may reduce the incidence. Maybe. How can this plan possibly backfire!
The next step, after the lawsuits of course, lawyers have to eat too, is to demand more in taxes to put cops back on vice. Maybe this time taxpayers will say "You know what? Policing this isn't worth the time. Legalize it.". But that's just silly of me, the religious lunatics and the misguided social justice types will want to step in to "protect the girls/family/values" when they should just let people who want to destroy themselves do it, and only put in laws to try to promote better safety, hygiene and abortion availability and minimize the actual social impact of prostitution.