I was under the impression that the reactor explosion wasn't the enough on it's own to destroy the Death Star but it was the big bang in a chain reaction of explosions which blow the thing to bits.
There is a world of difference between Geena Davis and Sam Jackson running away from an explosion in a building in the very silly The Long Kiss Goodnight and high speed ships racing away from a series of large explosions ending in the explosive destruction of a metal moon.
That said I really would like to see the Falcon not make it, go out in style but still go down.