There are no editors dedicated to categories. Think of them as free radicals. Even "editors with specific privileges in a category" can leave quietly, resign, move their focus to another category, etc.
Even aside from ontological imprecision, the question has no practical significance. The vast majority (probably well more than 90% of edits and possibly above 99% of edits) are done by editors who are NOT specifically listed as editors of the affected categories. The reason for this is simple and obvious. An editor who is a named editor on a category automatically has permissions in all its subcategories, so we suggest that each editor only retain listed permissions on the parent category. And ... an editor who is very active in a subcategory will tend to be quickly accepted in the parent category. And so forth, on down the tree. Many of the most active editors are "editalls", free to edit anywhere they think they can do a good job.
The requirements for an editor are: ability (to categorize things and describe them clearly), willingness (to work within the guidelines and the community), and interest in accomplishing the ODP goal -- helping the surfer without concern for remuneration.
.