Legal Question in Criminal Law in California

It's not true. Threats can be made via text, email, U.S. Mail, etc. But whether a particular message qualifies as a criminal threat will depend upon what it says, to whom it was sent, and a variety of other factors. You have not given us enough information to say whether this text qualifies.

Again, this is a threat the police are supposed to take seriously. if you take action and the desk officer refuses to file a report, contact the police chief and the DA office to complain. If all that fails, then your remaining option is a civil restraining order, but that will cost you attorney fees if you choose to hire one. You can file without counsel if you go to the court and get the info packet and carefully prepare the papers and evidence to file with detailed declaration that explains all the facts. Then go to the hearing and persuade the judge it is a serious matter. If serious about hiring counsel, feel free to contact me.