Some very good points.
. Now you lay out all the other info it is certainly understandable why they might not starting something with Fragile X.
Retts is still harder for me to see a rationale for not pursuing with NNZ-2591 considering they are already first to market there and already paying milestones and royalties to Neuren (tho NNZ-2591 royalties are higher I think?)
I would have thought the risk to them of Neurens share price rising much if they developed NNZ-2591 for Retts would be low - investors would just say 'well they're already paying Neuren for Retts, so it's somewhat like for like.
However, it also does sound like they have their pipeline pretty full and a new approved disease treatment is likely worth more than just upgrading an existing one.
(20min delay)