Why are some of them so saddened with Velupillai Prabhakaran's ping?

Because they are trouble-making LTTE members. They spokewoman went on TV in front of Westminster and declared openly, "How can the Sri Lankan government say they have wiped out the Tamil Tigers (LTTE). We are all Tamil Tigers here"! Britain is harbouring them because we are no friends of Sri Lanka and the Singhalese.