So, they're essentially saying that the 3.9 billion year old cluster of impacts (the 'late heavy bombardment') is wrong. They argue that the previously studied lunar rocks (that suggested that date) came mostly from a single impact basin (presumably ~3.9gyr
ago). This then skewed the stats.
Hmmm.
In one paper, they've dismembered not just that but also the timing of the whole Nice model about gas planet migration within the outer solar system.
Of course, what they do not consider is that Earth migrated inwards at the start of that bombardment cluster, following a serious impact and localised gravitational tussle (i.e. with Nibiru). The resultant debris stream would then account for the subsequent
cluster of impacts with objects with Earth/Moon composition.