It means that it is possible for someone to be wearing a white shirt and yellow pants (say), but the person in green shoes came from the set of a Wes Anderson film.
white, blue, yellow, and is otherwise undefined.
But we know from [1], [2], [4], [5] and [11], that the order must be:
A, B, C, D, E or A, B, E, D, C.
Which makes C either the older 12 year old or the 35 year old.
The key this is that D can't be a 12 year old without A being in slot 2, but A can't be in slot 2 because slot 2 is South Africa and A is Morocco.
Trying to reach the shoes + Vanuatu clue is a complete waste of time, paying any attention to shoes or clothing is a waste of time, it feels like there ought to be a way to narrow it down to one of those two configurations, but the clothing is too ambiguous, the shoes end up irrelevant.
What a frustrating puzzle, where half the clues are seemingly redundant.
I guess they were not optimising for a satisfying solving experience! (I'm not sure what 'expansion' means in this context, but it sounds like maybe the 'expansion strategy' referred to in the paper involved padding out problems with red herring premises?)