There are a few that are saying that, but you are right that the gun rights groups have never said it. Teachers, as a group, aren’t that different than most professions, in that there are wide range of political beliefs. Some are totally anti gun and will never embrace the idea of guns in schools. Others are interested in carrying at work and just want the choice.
I do have some difficulty understanding the fear that teachers will lose their guns to students, leave them in the bathroom, or otherwise have accidents at schools. Utah has allowed teachers to carry for years and there has been one minor incident...one....let’s get rid of the chicken little arguments. The sky isn’t falling.