This is edging into tinfoil hat terroritory.
I could buy sabotage of the tail (although I have to wonder just how hard it would be to get to the bolts INTERIOR to the tail section in order to loosen them).
But implied sabotage of the tail AND both engines strikes me as ludicrous as the JFK assassination theories that postulate multiple shooters from all over the plaza. It's just too baroque, AND unnecessary.
If I were sabotaging a plane by loosening components, I'd pick one critical item (tail OR left engine OR right engine), then fiddle with it and scoot. First, one is enough. Three is insane overkill. Second, sabotage to more components means more time spent farting around with the plane when you might get caught. Finally, it means you've tripled the odds of something failing prematurely on the ground, during taxiing, or during the launch down the runway, which would cause the plane to be grounded before it could take off and actually crash.
I'll bet large sums of money that whatever caused the first failure, the following failures were simply a chain-reaction and not due to sabotage at multiple locations.