The deep purple variety is available year around in most stores. The elongated lighter purple variety, also referred to as the Asian variety, is also available year around but in limited supply. Now to answer your seed question. I would surmise this inference to be pure conjecture. There is, however, some wisdom worth our attention.
All eggplants have a dimple at the blossom end that can either be round or oval.
Additionally, it is very true that the younger the eggplant, the fewer the seeds. Other features to look for in a good eggplant are plumpness, glossy color, heavy weight with the smaller the better. Avoid any which might have shriveled skin, bruises, or evidence of rot. Should your taste desire, there are a couple of ways depending on the final use. I will provide one way in my recipe below.