Actually Virginia is not "at-will" state when it comes to public education. Similar to North Carolina, Virginia has "career status" protection which protects teachers from being fired for political purposes.
This has widely been discussed and information provided on other threads. "Career status" was put in place for teachers to protect them from political firing. For example the biology teacher who teaches evolution in the classroom is protected from being fired from the school board made up of right-wing bible belters -- as long as the teacher properly taught the state curriculum. (Yes, this has happened in both North Carolina & Virginia -- and the courts awarded significant damages).
In the old days, teachers were fired every time the County Commissioners or School Board changed hands. Usually they would fire all the teachers who did not support them. "Career status" was put in place to eliminate these political firings and protect teachers.
This teacher in Virginia who strictly stuck to federal and state laws & guidelines in their teaching is clearly protected under "career status", and "at-will" employment will have nothing to do with the upcoming successful wrongful termination lawsuit.