Same thing happens when people talk to Siri, Cortana, Google and Alexa. You can be sure that Apple, Google, Microsoft and Amazon have all the audio. I think they even let you look up your voice queries and delete them. Whether they permanently delete the audio I don't know.
I see it as the same and people who are sensitive about those things just have to not use them. Wasn't it just recently that someone showed that iPhone apps with camera permission can record video, analyze your face and send that data to the app creator without you knowing about it? Plus that this was a feature working as intended, not a bug.
Granted that doing that with a kids toy is pretty messed up. However, Aibo isn't exactly something a normal parent would give a kid. It should be treated as any smart device that listens for queries.
Hopefully we these things will be addressed, but I think right now it's pretty much the wild west of smart devices and people need to be wary of what information they share with these types of devices.