Not quite sure this is fully transparent
There is something wrong here. The universe became transparent during the era of recombination, which preceded the era of reionization. See for example https://en.wikipedia.org/wiki/Recombination_(cosmology) and https://en.wikipedia.org/wiki/Reionization . It only stayed transparent after the ionization because it had vastly expanded and the gas/plasma was now spread very thin. Nowhere in its published papers does EIGER suggest anything different.
Yet that NASA guy somehow got the idea that, "The researchers ... showed that the galaxies are generally surrounded by transparent regions about 2 million light-years in radius. In other words, Webb witnessed galaxies in the process of clearing the space around them," leading our Vulture to talk of "Ionization began ... heating the cooled, dense, opaque and light-absorbing gas that filled the universe." Because it didn't.
What we can say is that the result of recombination was a "dark" universe in the sense that it did not emit much radiation, and what the new stars and galaxies did was to pour out stuff that EIGER could actually detect. It is only in this sense that the gaps between the bubbles are "dark". Maybe someone at NASA misread that "dark" and thought it meant "opaque", whatever.