M. Orlov's card index system: why won't he just follow the rules?

My ADHD husband and I recently agreed to use Melissa Orlov's card index system she presents in her book for dealing with chores. We have weekly meetings to discuss what needs to be done, then write out his chores on cards and place them by order of priority in the front of the box. All he has to do is open the box and take out the front card. 

Instead, he will either take out all the cards and stuff them in his briefcase, where they remain for the rest of the week and never get dealt with. Or he copies the chores onto a list, which of course never gets done either. He claims he is not trying to sabotage the system. 

But I, non ADHD spouse, feel like he won't even give it a try. Is there an ADD explanation for why he won't follow one basic, simple rule, i.e. only remove the front card and deal with it? I am starting to feel it has nothing to do with ADD and more to do with his feeling controlled and resenting the system or resenting me.

Meanwhile, the chores still pile up and end up either neglected or on my plate, and I am starting to despair that there will every be any change.