Why? To make you ask that question.

They want you being appalled about what they are doing, so they can go tell their base that you support a Muslim terrorist and murderer. They want to portray you as a deranged sociopath, more concerned about the killer than his victims.

All they have to do is commit an atrocity against a despicable person, and our outrage at the atrocity can be portrayed as treasonous: We are providing aid and comfort to an enemy. Their base gets to be disgusted by us, and driven to support them.