OK, it's Afghanistan, and anything can happen there. Although it absolutely should not be happening under the Grand Puppet President Karzai. But it is happening, and the guy will get the death penalty, and the rest of the world will be slack-jawed and disbelieving, exactly the same as when the Taliban blew up the Buddha statue.
Now look. I know Afghanistan has its own legal system. And it's pretty much pure Shari'a. So, is this right? Does Shari'a law say 'kill anyone who quits Islam' or does it not? Islam is supposed to be the religion of tolerance. How does Islam benefit by having members who want to leave but are afraid to because they fear they could be killed? How does Islam's stature in the world increase by murdering 'apostates'?
On a slightly separate note, I read some stuff a few years ago about 'Untouchables' in India discovering that they could become 'real people' by the simple expedient of converting to Christianity.