Your take on this is the same as mine: the birth certificate is a smoke screen. The real disqualification is the British citizenship of his father.
He has more than one disqualification.
1. Alien father
2. Likely born in Kenya
3. Was adopted by an Indonesian father and may have become (or most likely was) an Indonesian citizen.
4. Most likely used a foreign passport after the age of 18 when he travelled
For starters.