From what I recall I bought annona coriacea in January or February and they germinated relatively well, so the theory about old seeds may be or may not be correct. Some plants bear fruit irregularly depending on the place where trees are grown, the date of fruiting may vary. In addition, some annnona can be stored relatively long if certain conditions are met. If you do not believe the seller, ask him to take a picture of the fruit along with the newspaper in the background (so that you can see the date). If it is honest and the order is worth it, it will take a photo, and if not, then you have to answer if the seeds are fresh or not.
Anyway, if you don't believe the seller, wait until October and the matter will be solved.