So non-solicitation agreements are valid in CA? I know that non-compete's are not (to be clear, as I understand it, this means that Anderson is completely free to start a competitor to Tesla, but it does not in any way allow him to use any resources of Tesla in the formation and operations of said competitor), and had sort of just assumed that non-solicitation agreements fell into the same category.
EDIT: other comments have clarified - the crux of the poaching issue in this case is that he was actively soliciting Tesla employees for his competitor while employed by Tesla. That's a far more specific scenario than trying to enforce a non-solicitation agreement after leaving the company.
It seems that the current state of the law is that they're not categorically unenforceable in the way non-competes are, but that courts have found some limits in their scope. It also seems that there hasn't been a direct challenge to them yet. Either way, the issue in this case is Anderson's behavior while employed, so it doesn't seem like it will come up.
EDIT: other comments have clarified - the crux of the poaching issue in this case is that he was actively soliciting Tesla employees for his competitor while employed by Tesla. That's a far more specific scenario than trying to enforce a non-solicitation agreement after leaving the company.