So what if it was controversial? Some decisions are controversial. This one received more discussion, input, and thought than most other plans. Just because it did it doesn't make that decisions wrong or unethical.
Therefore, the parent's appeal to the IRB process as the harbinger of ethics is misguided.
If any IRB would deem a study ethical, then there's probably consensus among the scientific community on the cost-benefit tradeoff of the study. If one IRB deemed the study ethical, and if there're probably a lot of other potential IRBs that would not, then appealing to some sort of scientific consensus on the matter is a misnomer.