The guy grew up on a farm that raised corn. He mentioned this as a reason to give him credibility on his report that high temperatures combined with reasonable amounts of rain is not bad for corn.
Since corn was bred to grow in Central America and Mexico, this is a reasonable statement. It's rainy and hot down there. Corn doesn't grow ears below a certain temperature range because it won't pollinate and make the ears if it's too cold. Places like most of England.
Of course, if global warming kicks in we may see corn move out of the extreme south of England.
My wifes parents are already growing corn in Wales in there garden. This year is proving both very hot for Wales and also typicaly wet...