First of all, in the US, and in many areas of the western world, Muslims do convert to Christianity and do not get murdered. Second, it is highly doubtful that anyone other than a handful of kooks--even in the Muslim world--actually take these reporters' "conversions" seriously. The likelihood of them or their families ever facing any real threat is virtually zero.
Just to follow up with an example. Many people, including myself, have posted the Muhammaed cartoons on their web sites. Technically speaking, we are under threat of death. Do I lose sleep? Not a wink. These reporters, faced with a 100% chance of having their heads cut off vs. perhaps a one-billionth of a chance of being killed later on, did the math and made the obviously correct decision.
They do in Indonesia.