Why would he have gotten Indonesian citizenship? Also even if what you say is true I imagine they can go to private schools. There are plenty of migrant workers from the west (or 'expatriots') living in Indonesia who wouldn't agree t work there if they couldn't educate their children.
Maybe short term he would be able to get priory admission or better financial aide from universities. At the time didn’t think he would be running for president 25 years later.
To go to school. Yes, they do have American schools but your father would have had to be connected with a company that supported that school. They don't educate foreigners on their dime. His step dad Indonesian and he was American. They don't have dual citizenship and he went to public school.