Google home's speech recognition can't even reliably turn my lights on and off every time, why would I trust it to book a restaurant reservation? I'd expect to tell it to book a 6pm table for 2 and wind up with an 8pm table for 10.
If I call a restaurant and say "Can I have a reservation for 6 at 8:00" and they write down a reservation for 8 at 6:00 without repeating it back I won't know until I show up at 8:00 with my 5 friends.
I'm afraid I foresee this whole thing going quite hilariously wrong on the order of magnitude of Microsoft's Tay https://en.wikipedia.org/wiki/Tay_(bot)
That's a win, consider: It's the right restaurant, on the right date and 10 is larger than 2 so there'll be room enough. Ok, you have to wait two hours but given that this tiny place is normally so busy you have to book in advance what you lost in time waiting you will more than make up by the fact that you'll be the only people there expecting service.