Well, Jim, I'd place them together in a corner of the room with large "Reformed Former Buffet Eater" signs around their necks. Just kidding, of course; like I said, there's no easy or fair way to address the issue.
But I can't count the number of times people have said, "We never saw our tablemates the entire week," and that does make it hard for the DR to plan. Or maybe not--they presumably know how many no-shows they'll get on any given night.
I love freestyle and anytime dining!