That seems at best misleading at worst outright untrue...
Their own cloud connected app shows a detailed layout of your home's floor plan[0]. The implication of "navigation information via vSLAM, which stays on the robot" suggests that such a floor plan could never be sent to the Roomba App, since it is, that statement is suspect.
Plus the Roomba is updatable over WiFi without user intervention. So even if the above statement is true TODAY, there's no specific reason to believe it will remain true forever. They could push an update tomorrow, start collecting data, and then let you "opt out" if you don't want your intimate personal life shared with anyone who can pay.