I wonder though what the difference is between this method and the CO2 extraction method.
It sounds essentially like steam distillation, something that's common in chemistry labs. I'm surprised that there's much of a difference, and I would have expected the CO2 extract to be more aromatic. By doing the steam there's two big differences: the solvent, of course, is water, not CO2. There will be some difference in the nature and ratios of compounds extracted. However, the bigger deal will be temperature. The steam extract will be done at a much higher temperature. Normally in flavor extracts this extra heat is a detriment to the quality of the extract. I wonder in this instance, since hops are boiled during brewing, if the steam extract more closely approximates what happens when making a wet hop beer. Before retiring I was an analytical chemist and worked with both CO2 and steam distillation, so I'm hoping that something on the technical side gets published. Whatever happens, I will be looking for the beer!