I can certainly understand how ULIRGs (Ultra-Luminous Infra-Red Galaxies) can speed up the Reionization process. It also makes sense that ULIRGs would be far more numerous in the early age of the universe. This would also be the time that massive black holes are "bulking up" on the surrounding material and other black holes.
However, I do have a problem where the article says the Epoch of Reionization began 250 million after the Big Bang. The WMAP image of the Cosmic Background Radiation has a redshift of 1089, which puts it 379,000 years after the Big Bang and it is evident that the image is not completely opaque. Based upon the information I have found, the Epoch of Reionization began around 340,000 years after the Big Bang and lasted around 750 million years to reach its current level of ~10% opacity. Also, the first Population III stars are suppose to have formed between 100 and 200 million years after the Big Bang, which would have also contributed to Reionization.
I have no problem, however, with the article concerning the duration of the Epoch of Reionization. ULIRGs are tremendously energetic and I can see how they could speed up the Reionization process.