The author could have supported their statements a little better, but scattered throughout the articles are reasons like:
Ginger is harvested in winter and will decline in quality over time, so it may be best to harvest and use sooner rather than later. It will help with the side effects of meat stored for harsh and long times
Nutmeg is harvested in August and then proceeds through processing routes that may take enough time to complete and be ready for use by winter
Cinnamon is largely harvested after monsoon season June-December, so will be available for use in time for fall and winter time