In category options, there is an option to set the minimum tags required for a topic (Minimum number of tags required in a topic). I think an option to set the maximum amount of tags per topic in that specific category would be useful also. As well as disallowing them entirely.
It is somewhat possible to handle this with tag groups (Limit one tag per topic from this group), but not in the scenario where the tags also exist in another tag group which do not have this limitation enabled.
There is a work around for disallowing tags entirely in a specific category (at least for regular users). It can be done by creating a meaningless tag, assigning it to a tag group, limiting the tag group to only being visible to staff then limiting the category to that tag group.