Yes. I think many customers, as they work to setup what their portal page will have on it, see how to use categories to restrict access to workflows; create their own categories; put workflows in them; and use the 'WFA Configuration' 'Other' tab to hide example workflows, most ask next how to hide the built-n categories that are reporting (0) accessible workflows. Deleting the categories is a good short-term workaround but later they may wish they still had those categories around when they are in designer mode and want to look for, say, Decommissioning' workflows. So I'd think the ideal solution(s) would be:
1) not show a category in the left panel that has (0) workflows available to the user
2) or create an attribute for categories that can be checked for 'Hide in Portal'
Thanks,
Dave