You can't know how much these robots will save a store over 6 months, because all he said about them was the price. Hard to determine what a robot is capable of based on price alone. Also not included is total cost of ownership or how a breakdown will affect the restaurant. (If an employee is out sick, you call in a replacement. but what do you do if one of your robots is broke?)
It's also not as simple as replacing 1 employee with 1 robot because robots are specialized while humans are generalized. What I mean is that a fast food joint can run with 4 people. You don't really need a dedicated fry person since most of that job is just waiting for them to cook. Have one of the expediters watch the fries and drop more as needed. To run that same restaurant with robots, you would need a robot for each station (Presuming the robots are stationary). Fries, shakes, sandwich maker, breakfast etc. Then there's keeping things stocked. Gotta make sure you have enough buns, patties etc loaded in the robots. Are you going to have another robot to reload stock for the other robots? Who's going to clean the dining room? The bathrooms? Is a robot going to recognize and remove fecal wall graffiti, or is it just going to clean the toilet like it was programmed to do? To flat out state that replacing employees with robots will save the company money is pure speculation.
What this guy said was purely reactionary, and there's a lot more to going full robotic than just "replacing employees with $35k robots", and seeing how McDonalds doesn't actually own 81% of it's stores, I seriously doubt this is anything other than fear mongering: "Oh shit, if they raise the minimum wage, I'm out of a job! Better tell my congressman I'm happy with $7.25 an hour!"