Of the 33,000 streams of time he had inside his soul, Rowan was using 11,000 streams to blanket the entirety of this continent and maintain his domain, and he could not predict what would happen when he used the entirety of his powers to impose his will on this space, plus since he had spread out the streams of time over a large area and had not superimposed it on a single location as he had done with the Shiik, Rowan could not truthfully tell if he would be able to suppress a seventh-dimensional entity.
For now, he was not willing to find out, because even if he could, what was before him here was simply a Memory and not the real thing, and because the Mother of Poison would not be staying here for long, he did not want to antagonize her further.
If he was a betting man, he would still bet that he would lose, because the higher dimensions were too expansive to be entirely shackled by quantity.