Probaby or at least a serious study
Meteors have been hitting he planets for billions of years. I think it pretty naive that humans think they can do something about it.
You raise a very valid point. The kind of effort that would need to be put into a deflection effort would be formidable and, sadly, if an extinction level event was to approach the earth, there is every possibility that we would only have two or three weeks notice which simply would not be enough time. Our best hope, in my opinion, is two-fold: 1) we build and install a satellite-ba<x>sed weapons' platform like a rail gun that could react with alacrity. and 2) we invest considerable resources into terra-forming off-world. It isn't a case of 'if' but 'when' and our best hope of surviving, in the long term, is if we get off this planet.