I am not really a fan of kitchen sink UI, this is kind of an obscure option that most people don’t need.
But! Since this is limited to category I wonder if a New Topics entry in the category notifications list would work. Conceptually you pretend that every new topic mentioned you by @name and follow the same code path. Then you are only notified of new topics and the notification state for individual topics is still “tracking”.
Hmm, maybe a single check box makes sense, at the bottom.