Good question. Summary indexing does not count against licensing, ie, mining data that has already been indexed and storing the results in a new index.
If the dbquery command collects data directly from a database, and the splunk summary stats search commands can search those results and populate an index, then you may have found a way around licensing. Hard to believe tho, the licensing code is pretty well baked in.
Have you tested it? It should be easy enough to test.