Re: Suddenly it happened all at once? Huh...
'Why don't you write something up for a research grant, kid? You seem to have guts.'
Hey, his speculation is just as valid as theirs..chances are he isn't in that stratified section of humanity who get to apply for said research grants.
No doubt out there in academia some astrogeologist and his team of merry postdocs are sharpening up their quill pens in eager anticipation (yaay, minimal work and another published paper with my name on it!) with this particular theory being posited as an alternate explanation for the '12 ± 3 parts per million difference in Δ17O between Earth and the Moon'
From the Abstract as well (as paper is paywalled) '...The observed small compositional difference could alternatively be explained by a carbonaceous chondrite–dominated late veneer.' Umm, like maybe the meteorites that @Magister Phillip mentions, so they've covered their bases.
Disclaimer: Have helped write grant proposals, having spent waay too many years in Academia. I've seen many grant proposals submitted I swear were written up by 12 year olds*, sadly, thanks to the particular names attached, some of these got approved (if the taxpayer only knew what some of the old SERC funding went towards...)
*I'm talking about the ideas behind the proposals, not the language used to couch them.