Are you saying the speed of light is constant in all frames' date=' or do you mean just the ones that scientists agree that the speed of light is constant in?
Or are you perhaps [b']defining[/b] a "frame" as that which the speed of light is constant in?
Just a suggestion as I think this is a great forum with some very knowledgable and smart people on it (yourself included) but if we had a list of agreed definitions it could save us some grief and keep us on topic.
I know I am as guilty as anyone in using the wrong terminology at times but I do not do it intentionally and try to "flag" it in some way if I'm unsure.
Outside of inertial frames I cannot think of any others offhand that the speed of light is constant in.