I've heard that, too, but not sure it is true. Think about it - a lot of eggs can stand cold because of a freeze/hibernation style cycle in nature, but they can't stand heat. Once the flour returns to room temperature, who's to say those eggs won't hatch? It's no different than a flower bulb that lays dormant in the winter, then springs to life in the warmth of the summer.
If I were to anything, it would be the heat option. Heating at 180 degrees minimum should kill and sterilize the flour.
Either way, I've never had a problem (or seen bugs) with my flour sifted through a fine mesh strainer, then stored in vacuum sealed jars or airtight containers. Perhaps I've been lucky...God only knows!