The prisoner obviously will kill himself by starvation if left to himself, which is somewhat odd: for in Islam, suicide is an “unforgivable sin.”
Apparently blowing oneself up with a suicide bomb also does not count.
The answer is that we are taking Islam much too seriously, as if it were actually a valid, respectable religion. World-wide, predominantly Moslem countries have high crime rates, low economic productivity, poor work-ethic, tendency to plunder neighbors, poor social standards (as in treatment of women and children), barbaric behavior, cruelty, mass ignorance, and lack of much sense of the enjoyment of life. Islam is, truly, a gutter religion.
Anything goes in jihad, though.