I disconnected my Roomba from the network right after programming its schedule. It still works great, following the same schedule for 7 years.

I recently bought a cheap Chinese roomba clone. It comes with a remote control so you don't need to connect it to the internet. I do have to press a button to start it but it works great.

If you care about your privacy, choose products appropriately and/or take 5 minutes to protect yourself. Most people don't seem to care, which is their choice.