Not so.
To heat treat for insects in cabinet hardwoods you start at 120 degrees and go up to 140 degrees if you want to kill the eggs, or for for hard to kill insects like bed bugs.
Specifically, drugstore beetles, minimum heat is 125 degrees for four hours to kill all forms including the eggs.
Restaurants hold food at 140 degrees as the danger point for food is between 40 and 140 degrees. Proteins begin to coagulate at 140 degrees F, at 150 degrees the starches gelatinize and begin absorbing water from inside the insects cells.
Charring of grain begins around 220 degrees. It was once used to preserve grain in ancient times and has been studied by archaeologists to understand grain found in digs that has survived repeated wetting and drying over thousands of years.
The ignition of most grains isn't going to happen until it is over 300 degrees.
So, used with a modicum of common sense, using heat to kill insects in feed is both safe and effective.