Uhhh, ejections did not produce the "secondary" craters
The ejected material lacks the velocity necessary to produce much of a crater, or the necessary size... even for material accelerated to orbit, it slows to frei-punkt on re-entry...
Again, all the comments in this article ignore cometary impact, and Shoemaker's revision of his earlier thinking on it... and there aren't enough small objects in the asteroid belt to account for all the craters... wait until they start to work with the Cassini images...
That said, the people interviewed fundamentally got it right, which is that as things now stand they do not have a clue as to any of the dates for any Martian processes...
ep