Religion, something that I can never understand

Man challenges dead half-brother's conversion to Islam

...after the post mortem, a hospital staff informed the deceased's family that the body could not be released to the family as the deceased had converted to Islam at the Penang Religious Affairs Department.

I'm was stunt when I read about this, is it true body of a Muslim cannot be claimed by their family members who are non-Muslim? Seriously must they treat religion like citizenship which once cannot have dual citizenship (beside a few countries)? All religion in general are teaching their followers to do good deeds, be be humble and kind. Can't a person embrace two set of teachings?
In my opinion it shouldn't be a problem at all, just an analogy. Hinduism believe that they shouldn't eat beef because it's a symbol of their god and the cow are working hard to help them earn their living; and the Muslim believe that they shouldn't eat pork because it's dirty and diseases could be spread from there. If one want to follow both religion, they can just choose to eat fish or be vegetarian.

So many blood was shed for the invisible 'superhuman' if they really exist is this what they really wanted? Or a small group of people had found out the truth behind the teachings and make good use of it to influence other people to perform tasks for them? Tasks like Holy bombing, holy fucking etc etc etc any verb with the Holy prefix (holy shit included?).