Yeah, I don't think the guy was planning anything immediate.

If nudged successfully, the asteroid would do a loop around the sun and head back towards Earth, before slingshotting itself on Earth's orbit...

'Do this a million times and the Earth will increase its velocity by the amount we need...'After a million fly-bys, the Earth is in its new, up-town orbit...'And as we have a billion years for the move, this means we only need one fly-by from the asteroid every one thousand years.

'Do this once every thousand years, and over a billion years we can move the Earth enough to keep its temperature constant while the sun brightens.'

There's no way to tell if it would even be required for many thousands of years, our entire concept of climate change is based on a few decades of weather data and temperature readings from airport runways.