I think reactions are heavily influenced by individual circumstances, Terror frightens many, they fear expressing their feelings openly and becoming targets of the thugs. It's a bit like those in western society who were paid protection money in order that they or their business were not harmed. If I am honest  I experienced less emotion when the lebanon was bombed than I did over attacks in Paris, I was also shocked by the downing of the Russian airbus and the bombings in Ankara, yet the latter saw many locals refusing to observe a minute silence in respect of the french atrocities during an international football game. Deep conviction to the Muslim faith and an unswerving loyalty to the preaching of imams  sometimes prevents rational thinking or expressions of grief toward non muslims. So many of my observations show a community wedged in the past and unable or unwilling to adopt change. If they wish to remain that way then perhaps they she follow the example of others by getting on with their lives and not interfering with the lives of others.