It's like a platinum toilet lid. Costs way more than needed to accomplish the task and cheaper alternatives are probably better. Real asteroid hunters aren't pushing this for damn good reasons.

You really ought to stop by NASA's NEO site some time and explore the links to people doing fabulous work in this field. Also read some of the great reports at Morrison's site so you might understand why large comets are beyond our ability to divert. You might even start to think we need as big a heavy lift vehicle as we can get to give us the greatest range of possible options to divert potential impacters.

Regards,
Mark