The difference here is that the Biogen drug was worthless. The FDA will be eager to approve a good drug against Alzheimer's.
People should understand the FDA's mission, which is "Protect consumers/patients and enhance public health by ensuring timely access to safe, quality FDA-regulated products." It is not to oversee the development of drugs to the greatest extent possible. They understand the perfect is the enemy of the good.
What we know about blarcamesine after this trial is that the FDA should welcome its submission. There is a lot of public health to be timely protected by not requiring a lengthy second trial of a safe, efficacious AD pharmaceutical.