We've already established that it would deflect a wheel. Probably a nose cone too. It might even have stopped the spring that hit Massa.
Look, Deuse, we all know you hate the idea of any type of these devices, as do lots of people (me included), but you have to accept that at some point it will come in. Perhaps the halo will be delayed again until 2019, perhaps it will be scrapped in favour of the canopy or the self-deploying device designed by the ex-Ferrari engineer or perhaps we the whole project will be canned indefinitely, but the moment that another driver's head is threatened by a piece of debris then we will have a device installed. It is going to happen at some point.