They fit the look of the robes but it doesn't make sense. The Trade Federation were just a means to an end and when that end was achieved Vader killed their leaders and I assume Palpatine took charge of their assets.
If the Neimodians were to be on any side it would possibly be with the Rebels (if they would have them).
If they served the Emperor in any capacity it would be in chains rather than robes of state.
Nice mockup though.