Passover in Indonesia

Several years ago, my family and I attended a Passover Seder in Indonesia hosted by a Jewish couple doing post-grad research there.  The hosts were unable to find many of the traditional items for the Seder and gave interesting explanations of the meaning of each and of how they had settled on substitutes. We're non-theists, and so had no religious qualms about being there.  But there were also a number of Indonesian Muslims who came.  At the time, I admired their tolerance and their interest in other traditions.  But now I wonder if they attended at some risk to themselves.  Perhaps the risk was minimal, given that we were in Yogyakarta, one of the most liberal areas of the country.  But I would guess that the danger could have been considerable in a more religiously conservative area, like Aceh.