I have never seen a plate with Arabic writing in the US. I think as long as they have Western characters, that will be fine, but the customs clearance/control people who will ultimately let your bike in will decide. You should contact authorities in that department at the port of entry you plan to use.
To answer rukitamo's hijack, it's very simple. You don't mention your country, but regardless, insurance companies in general will first look at your driving record, the type of vehicle you are driving, and secondary things like credit ratings, age, criminal record and marriage status.
There's no problem at all with your son's situation. Just get insurance immediately because it's illegal to drive without it. The only thing you'll find is that without any history of having insurance in the past may result in somewhat higher premiums, but a clean driving record and a valid driver's license is far more important.
Hope that helps
Better to be an idiot than a crook.