Just to clarify, the Imperial Steward is not the Vice Premier by mandate. This position was created (by me) essentially to "call the vote" during a time when people would endlessly hold up the passage of Senate Proposals by insisting that they should be allowed to debate points indefinitely kind of like a filibuster. Other than that OOC duty to bring a timely vote within 3 days and censure senator players from being rude to each other, their IC duties are running the Senate offices and managing Senate administrative staffers. They're basically a professional bureaucrat who can be easily NPC'd in the absence of a player should the Premier's player disappear.
That said, I suppose the Vice Premier could be appointed Imperial Steward because only the Premier, Senators, Taisho of the Star Army, SAoY officers, and Empress are barred from being the Imperial Steward.
Anyway. However the vote turns out, it would be very awesome to see the Premier/VP players do some fleshing out of the civilian departments. The Yamatai Government headed by the Premier has the potential to be kind of like a civilian version of fleet management.