If this piece of rock was headed to Earth, there would be no chance of deflecting it, because we spotted it too late. We need to fully fund NASA, to not only find these asteroids, but to give us a chance of deflecting them when necessary.
while the size of this asteroid woudn't have caused much damage, if there was an asteroid big enough to do critical damage, I personnaly prefer not being informed, as it will only create panic and we might destroy ourselfs before it hit.
Detecting could be good as long as solutions are put in place to deflect such asteroids, there are many serious studies on way to deflect such a thing such by using gravity or ion and co trust to change direction by just a few seconds which would in long distance make it miss the earth by a huge marging