In allowing butter, we wanted to give everyone more options for the consumption of fat. If someone reacts adversely to dairy, then regardless of the level at which they are playing, they should avoid it. At the same time, just because someone doesn’t react adversely (or recognize their reaction) to dairy doesn’t mean it should be allowed.
Some people have never given up dairy long enough to know if they are sensitive or not. Remember, this is a challenge and a game…and games have rules. These our ours. We didn’t create the rules from the standpoint of being nutritionists (we are not). The guidelines are from widely accepted and acknowledged sources and there are going to be rules in the game that don’t align 100% with everyone’s personal experience.