Hmm. Is acting as a foreign agent, at the same time as serving in Congress, an act of treason?
Sigh. Treason is specifically defined as giving aid or comfort to the enemies of the U.S. or making war against the U.S. We have not had an ‘enemy’ since WWII, the last time Congress declared war against another country.
There’s a reason the Founders were careful to so carefully define ‘treason’. In England, treason could be charged and brutally punished (as in hanging, drawing and quartering) for doing anything that upset the sovereign. Henry VIII was easily upset and the Founders wanted non of that here.