I'm afraid what's missing for me is the motive. What on earth would the US want with a plane full of multi-nationality members of the public and an ageing commercial jet? They have no beef with Malaysia or China (where the majority of the passengers are from), certainly not enough to kidnap civilians.
The reason Diego Garcia isn't being mentioned is simple - it's a secret military base. You can't go making the secret military operations of the world's biggest superpower public knowledge every time civilians go missing...
