I haven't read a quality translated piece on this development of events but it seems pretty straight-forward. It looks the group that is set up to manage Tintin threatened legal action against a Lausanne gallery for displaying paintings by Atak intended as an homage and/or commentary on that worldwide set of ideas and intentions. Rather than fight it, due to the resources perceived necessary to do so the gallery closed its doors after the first day the exhibit opened and gave a couple of statements to the press, one right on the physical door of the gallery.
I don't know how the actual laws work, but I think there's a general idea that this kind of expression is legitimate and be allowed. It kind of reminds of the feelings a lot writers and artists have for the Edgar Rice Burroughs estate, that the zealotry for constraining the rights and channeling the money that comes from use outpaces the public good that comes from allowing these ideas to be engaged by artists, at least to the point that there is some general bullying perceived.