Such adult behavior, since he was born with divided loyalties, would prove he has exercised divided loyalty thus disqualifyiung himself as 'only' a natural born citizen.
You are confusing behavior that may be disreputable or dishonest with behavior that has a direct legal effect.
The laws and Supreme Court decisions have made it very clear that renunciation of American citizenship only occurs as a result of formal action undertaken by an adult citizen who is fully informed of the consequences of his actions. It does not occur because someone files papers claiming foreign citizenship.
You may think (and I may think) that doing so is despicable and shows the person to be unworthy of being our president. But it doesn't change his legal status as a citizen and therefore his eligibility under the constitution to be president.
Perhaps an analogy might help. If I lie to my employer or wife, perhaps to cover up my immoral behavior, that is despicable. Those who find out about it might decide they don't want anything more to do with me. But the law generally isn't involved.
Now if I tell the exact same lies, for the exact same reason, in a court of law while under oath, it's a felony and I'm liable to prosecution for perjury. Perjury, unlike lying in general, changes my legal status.
If Obama falsely claimed foreign citizenship, which BTW nobody has proven to be true, it may illustrate his unfitness to be president, but it doesn't change his eilgibility under the Constitution for the office.