Well...
Legally a restraining order is not any sort of conviction, arrest, or criminal charge. In a legal sense it is more of an abundance of caution, since there is little due process involved.
I've never heard of anyone being asked about a restraining order at an interview. It does not fall into the usual category of questions that employers may ask, and it may very well be illegal to ask depending on the state.
I would find out if restraining orders in the jurisdiction in question are a matter of public record and whether they can be easily found in a search of court records. If they can only be found by searching the name of the plaintiff, then it would be hard for anyone to learn that an order had been filed against a given restrainee.
But with all that said...what the &%*% dude!?!?! Whatever you did to earn a restraining order is NOT the sort of behavior that employers expect of pilots. You had better hope this doesn't wind up on social media...maybe best to close your FB account at this time.