First of all, he isn't a dual citizen any more. He was a dual US/Kenyan citizen at birth, but he lost his Kenyan citizenship in his early twenties.
Second of all, I support the following the Constitution, and there's nothing in there preventing a dual citizen from becoming president.
This is simply your interpretation of the Presidential eligibility clause of the Constitution and certainly not a fact as you try to state it as. Just simply your opinion.
Myself I absolutely hold the opinion that the term ‘natural born citizen’ was intended to mean having two American citizen parents at birth. I have read much of the arguments that claim so and also much of the arguments that claim that it does not. Up to now at least I have been more convinced by the arguments claiming dual citizenship at birth to make someone ineligible.
Even by using just simple common sense anyone could agree that allowing someone with dual citizenship and dual loyalties to other nations to be dangerous to a nation for the position of President.
Obama of course even showed his loyalty to Kenya by illegally going over there as Senator to campaign and influence their Presidential election.
Then of course there is also the issue of his possible Indonesian citizenship as well and the issue of his real name.
The issue should have been heard in Court and so it is also a travesty in my opinion that the Courts have denied hearing any of the cases so far.