2nd part)
The Çatalhöyük people dealt with death by bounding the person tightly, in a flexed position. And burying them underneath the floors of the houses, so just a simple grave.
1st part) People deal with death differently, so when someone goes into a settled community with a different way of death will seem weird and creepy. So to fit in, they would probably change it. Or they will be shamed, avoided, even killed.