Dr. Missling has a finite amount of time and money. He's also in an impossible situation because if he spends time getting other trials started it'll slow down Rett and Alzheimer's and he'll be criticized for not getting those across the finish line ASAP.
Dr. Missling's attention appears to be shifting away from the science and more toward business strategy. He's heard shareholder demands for revenue immediately, recognized Rett is the best path forward (and we get a priority review voucher!), but that means a few other trials have to wait a bit longer in the queue.
It's really a first world problem if you think about it. Sigma-1 activation could play a role in so many different brain functions that we don't have the time or money to test them all simultaneously. Some indications will have to wait their turn. No big deal, as long as there's progress being made with Rett and Alzheimer's it's all good.