If we go back to the intentions of the Founders, any sort of law requiring a President, VP, or member of Congress to divest him/herself of all business holdings would have been unthinkable. The intention was that "serving" as any of the above was to be a temporary hiatus from life in the real world. They were supposed to take a bit of time to run the government, and then go back to doing whatever they did in the real world.
What was George Washington when he wasn't generaling or presidenting? He was a gentleman farmer, right? Would anyone suggest that during his time as President GW should have been barred from telling his workers what to plant, and when, and where?
Modern politics seems to have completely lost sight of that concept -- which is one more reason why we urgently need to establish term limits for congresscritters.