It’s not inexplicable. That means there is no explanation.
It was hijacked, the hijackers made it turn toward some other destination and at some point, blew it up.
Occam’s razor. The simplest explanation is usually the right one. Fake passports, unused tickets, Iranians...The math here is not difficult unless one is intentionally blinding themselves from it.
What’s the point of turning it off course, only to blow it up anyway? Other than to confound searchers?
Ok, then this is inconceivable.
Presumably smuggling a bomb on board the plane would be a lot more difficult than getting hijackers on board.