While that may be true of Indonesia, it is not true of the US. Since Obama is, and was, a US citizen, neither he or his parents could give up his US citizenship while he was still a minor. It does not matter, in the slightest, what another country decides to do. Obama was a citizen of this country, therefore the US laws apply and Indonesian law does not.
Barack had a window of opportunity to restore his U.S. Citizenship until he turned age 18 and 6 months. Even so, restoration would have required an Oath of Allegiance which would make him a naturalized citizen.
He had no need to restore his citizenship because he never lost it. A minor cannot give up their US citizenship. Period.
I don't know where you are getting your citizenship laws from but you need to change to someone reputable. This person, quite obviously, does not know what they are talking about. Since Obama was a minor, there was no removal of US citizenship. When he came of age he would have had to renounce his citizenship in order to lose it. He did not do that.
You have the way things are done completely turned around.
Any U.S. Citizen, regardless of age, can voluntarily request a Certificate of Loss of Nationality from the U.S. State Department. Any discussion of age restrictions is concerned with involuntary Loss of Nationality.
It's xenophobic to think non-citizens of the U.S. can come to America and naturalize and a citizen of the U.S. would not and could not naturalize with a country other than the U.S. Some countries, like Indonesia, do not allow dual citizenship. Consequently, they would require an applicant for naturalization to demonstrate a Certificate of Loss of Nationality before they can become a citizen.
Step out of the U.S. Some countries consider themselves equal to the U.S. and are not shocked when an American shows up and volunteers to naturalize with their country.