Anyway a DWL is not a "frigate" in any sense other than Taldren's silly way of grouping ships. And whatever its command rating, it certainly IS a command ship (albeit one intended for smaller ships).
My feeling on the DND issue is that the Lyrans would have NEVER allowed such a ship into combat unless they were strategically in an extremely desperate position (which historically they were then). Doing so meant risking an extremely valuable and expensive DN upgrade, and for what? To get another destroyer on the board? It was a unique situation which resulted in a unique ship being used in a very limited way.
Anyway the question that should really be answered is a larger one, specifically regarding unique and conjectural ships and how they fit into PBR.