Sorry, but the plane was too high for a shoulder fired missle.
My uncle, now retired, was a senior mechanic for TWA at the time. He was off that night. He says the center fuel tank theory is baloney.
It wasn’t too high, it was just too lucky a shot. It was at a low enough altitude, flying straight ahead, it would take a well placed lucky shot, though, I agree. Bordering on unbelief that a MANPAD did it.