I skimmed the article again and didn't find any obvious equivocations regarding IQ and intelligence.
But, regardless of this, I think solving problems requires creativity, not intelligence. Creativity seems to be independent of knowing how to do IQ tests. It's also, pace the author, independent of the environment. The main limiting factor is whether you want some particular knowledge.
>sufficient number of communicating, above-average intelligent agents could expand the intellectual environment
Haven't we already got that, with the internet?
Groups tend to be dominated by groupthink which is why creative individuals are aloof.
Nevertheless, a young group of AGIs would be fairly isolated from humanity simply by virtue of being non-human. So, though their starting point would be determined by the state of our knowledge at their birth, they may well make rapid progress for a short period, rather like the renaissance or the USA in the late 1800s when the nation was young and expanding. Then presumably they would fall prey to groupthink and pessimism just as most adults and nations do eventually. Progress would slow considerably.