lawfag jr here. I have done some research on it. The only time it has ever happened was during the Civil war. The congressmen did exactly what Mad Max is doing. He was arrested and tried by military tribunal. Found guilty and appealed it. The SC wouldn't touch it because Military Courts were not in there constitutional authority. The case was later revisited in another post war case. In that case it describes a scenario where the Military could hold the congressmen but not be the presiding court. They would have to hold the person until the civilian courts were back in control. Here is the Wiki on the subject if you want to take a quick read.
https://en.wikipedia.org/wiki/Ex_parte_Vallandigham