Personally, I don't see anything wrong with two people rolling around and trying it out by mutual consent. From the lineage on the website of the dojo in question I know for a fact that their instructor Shigeho Tanaka did just that. So did Morihei Ueshiba, Sokaku Takeda, and just about everybody from that generation. What exactly is the problem?
Did they throw down publicly, or within a dojo or some sort of sanctioned event? Did they break the laws of their place and time? Should they have participated in such thing? Has society changed a lot over the last several decades?
I'd just invite the lady to come train with me for a while. That way, no fighting, and everybody learns. If what I like to do suits her, great. If what I do is beneath her skills and abilities, I learn something. If what she does is not up to the dojo's snuff, we've got a new student, I've got a friend, and Bob's your uncle....
It is hardly ever a single incident will get a person sent to the sin bin. Especially in a dojo.