Most Helpful Guy
Since he hasn't done anything physical or even verbal to you when he comes to your restaurant, there isn't much history to go by.
I would recommend you talk to the police and ask what can be done. If nothing else a police report is on file. Let them know you purposely changed your phone number because of his abusive messages. It sounds like care and caution are necessary here.
The restaurant is a public space and he's allowed to go there and order food like anyone else. As long as he doesn't do anything more than order food and leave, there isn't much to go on. Fear is your #1 enemy, not him. That doesn't mean you should ignore his actions. Be careful, use your head.
Most Helpful Girl
What I am Most "Worried" about is when the doors close and you are left to Leave? And even if if still Open... You are still Open Prey for him when you do Leave your job.
Yes, go to the Courts and Ask for this Restraint. It's Best to be Safe than sorry.
Also tell your manager you would prefer if he would Not eat where you are Working.
I have seen Way too Many cases on True Stories, which I Watch as much as the News, and this One, hun, is a Time Bomb just Waiting to Explode. Especially if He would See you with a New guy in Town.
Good luck ans Be safe. xx