That's fair but their serving utensils don't need to make any contact with your tupperware. As long as it looks clean enough to sit on their counter while they convey the food into it, that should be sufficient right?
EDIT: The "health-code BS" bit is from my experience once, requesting a restaurant to refill my water bottle when I was leaving. Unless they're dipping a water hose into my bottle to fill it, thus bringing water in my bottle into contact with their hose, I fail to see the health issue.
Actually I'm with them that there's no guarantee my tupperware has been properly sanitized, nor do I trust the general public to sanitize theirs when you have so many people who will gladly double dip into communal foods.