Look I don't believe in this theory. But the part you are missing is the "And maybe the explosion turned out much larger than the thieves expected..."
You look at the explosion see how big it was and say "nobody would be willingly cause that big of a problem to hide a smaller crime." But when you think that you are thinking backwards. You know how big the explosion was, therefore you conclude whoever did it must have known how big the explosion will be. That's not really correct. They might have underestimated for technical reasons, they might have underestimated because they are incompetent.
It is kind of like asking "who would burn down 22,744 acres for a gender reveal party?" Nobody intentionally, that's for sure. But the Earth is full of stupid and/or incompetent people.
You look at the explosion see how big it was and say "nobody would be willingly cause that big of a problem to hide a smaller crime." But when you think that you are thinking backwards. You know how big the explosion was, therefore you conclude whoever did it must have known how big the explosion will be. That's not really correct. They might have underestimated for technical reasons, they might have underestimated because they are incompetent.
It is kind of like asking "who would burn down 22,744 acres for a gender reveal party?" Nobody intentionally, that's for sure. But the Earth is full of stupid and/or incompetent people.