She's offended because your quote refers to women. She can't explain it because either she doesn't reallly know why she's offended, or she just figured out she was being stupid and she'd sound even stupider trying to explain.

Point out that the main thing with cats is you can never figure out why they act the way they do, and she just gave you a nice example.

If this is someone you have to be nice to, explain that cats behave regally and dignified (forget to mention they lick their assholes) and are self-sufficient (forget to mention they need somebody who can operate a can opener) and good judges of character who do not suffer fools lightly (forget to mention that fools with canopeners or cashmere laps are just fine).