Why would Stanley renounce her son’s citizenship but not her own? It is possible that she considered him to have dual citizenship either Indonesian or Kenyan as well as US and that is why she crossed out his name.
When you consider all the Irish-Americans who applied for Irish citizenship and have not lost their US citizenship, or the immigrants who became US citizens and are still considered by their native lands to be citizens, or the children born here to immigrants (like the American born children of my French neigbors, who are French citizens according to France) - it is obvious that dual citizenship does not void US citizenship in practice.
When it comes to the presidency, maybe it is a different story. But I would not hold people liable for the decisions made in their behalf while they were children. If the French-American kid down the street wants to be president someday, let him renounce French citizenship. OTOH if his parents take him back to France, raise him as a French citizen, and he lives as a French citizen after the age of 18 - too bad for his presidential ambitions.