Botanists do not categorize anything as vegetables. According to wikipedia, eggplants are a botanical fruit.
Here is where the confusion lies in this whole fruit/vegetable debate:
There are two definitions for the word "fruit". One definition is scientific, the other is generic. For a botanist, a fruit is the flowering ovary of a plant that contains seeds. A lot of botanical fruits aren't even edible.
To a chef, a fruit is a sweet, edible structure from a plant.
For a botanist, nothing is a vegetable. This is because this word in not part of their nomenclature. Broccoli, corn, carrots, celery, potatoes, etc. are not categorized as vegetables. A botanist could not categorize an eggplant as a vegetable even if they wanted to. A lot of things commonly referred to as "vegetables" are called "herbaceous plants" in botany.
For a chef, a vegetable is a savory plant. Pumpkin and rhubarb are considered both fruit and vegetables in the kitchen. This is because they are used in sweet and savory dishes. Tomatoes are never used in sweet dishes, so they are considered to be vegetables, even though they are botanical fruits.
Eggplants are used in savory dishes, too. For a chef, an eggplant is a vegetable.... for a botanist an eggplant is a fruit.