First, her argument is internally weak. What, the physical conditioning will be of little benefit? The hand strikes will simply not be useful? The reflexes cease to operate when she is in her mufti? The skirt reduces any footwork (not even talking about kicks here) to utter uselessness?

Well, I think it has something to do with the fact that she wouldn't wish to stop wearing skirts during practice either. I don't know if hakama "count" in her book.