Assuming Anavex has the biomarkers for AD, the FDA would use that to grant AA. If there is also clinical effect, that will give Anavex the opportunity for a traditional approval process, as well. (I think having both, in practice, would strengthen either NDA choice that Missling may make.)
For AA, there is no need for Anavex to perform better on the biomarkers than Biogen or Lilly -- which is a good thing, obviously, especially considering how well Leqembi removes amyloid plaque. This is not the same as an efficacy determination, where an SOC can change for the better. Once established, biomarkers do not change.
You call it weird, I call it cynical and ironic -- because, in the end, despite what the FDA believes, these biomarkers are not good ones; they aren't really predictive of efficacy in improving (or even establishing) Alzheimer's. And in the end, of course, with an accelerated approval Anavex will eventually have to demonstrate better-than-SOC efficacy in another trial in order to receive a permanent approval. That day of reckoning is merely delayed. So it will be meaningful to show blarcamesine has the best clinical effect.
Even for a biomarker process, the FDA has to conduct its statutory risk/benefit analysis and it is therefore a great help, for the accelerated approval process, that blarcamesine appears to be so safe. If anything, people here are still underrating this advantage. I think the convenience of a daily Anavex pill also adds to that benefit.