I don't think counseling could hurt, especially if you're lucky enough to find someone familiar with gifted kids. If your son knows enough not to throw tantrums at the school, then there must be either some deterrent there that is not present at home or some benefit at home that is not present at school. It may turn out to be that he feels safe enough at home to release the pressure valve, in which case you can work out different ways for him to achieve the same result.
I sympathize; it's hard to hear your kid talk that way.
