Obligatory IANAL, but...
Generally a search warrant needs to be issued by a local authority, and that requires the crime to be prosecutable in the place where it was issued.
So in theory, California is potentially able to refuse requests to search for things that are not illegal in California but may be illegal somewhere else.
That being said, it looks like there are specific practices in place making it easier to issue warrants for electronic data like this scenario, even across state lines.
And in this particular circumstance, the alleged offense is even illegal in California (abortion of a viable fetus), so it's a bit of a moot point anyways. A Californian judge would have issued this warrant if a local police department requested one.
More time will definitely be needed. I'm glad they caught it and acted quickly enough to prevent more vandalism from occurring, but until we know how the account was compromised and what else they may have gotten in the process, it's still a situation to keep an eye on.