A Canadian conservative is one who believes in limited government and that the government should stay out of our wallets and out of our bedrooms.
In this case - the terrorist abandoned Islam when he decided to kill people.
Also - if none of the immediate family claims body, and no prominent Islamic group claims body, and the state must then deal with it, I see no reason why "religious acceptability" should have much bearing on things.
Of course - the other option would be to bury him in an unmarked grave in the prison grave yard where his brother will spend the rest of his life.
In my city you get a cardboard box in an unmarked grave beside the drain ditch at the edge of the woods behind the maintenance building in the largest of the city owned cemeteries. Some people do actually donate real burial plots they do not plan on using anymore that are used to help bury poor people who want to have a funeral. Churches will sometimes take up collections to help pay for indigent funerals when asked. We have a lot of churches, so it adds up quick even if only a few people throw in a few dollars.