Surely that's a typo, Chris? Every reference I've seen has talked in terms of two months, rather than two weeks. And I've frozen pre-ferments for much longer than that.
I also don't understand the reference to prolonged cold. Exactly what does she mean by that? I store my yeast in a 0-degree freezer for months at a time, and the yeast wakes back up and does its thing as it warms up.
It occurs to me, too, that if what she says is true, nobody in New England would be able to make sourdough. Given the length and depth of your winters, all the wild yeast would have died long ago.
Increasing the yeast by 10-25% is totally unnecessary, IMO. If some of the yeast does, indeed, die, all it means is that the dough or shaped loaf will take longer to rise. But so much depends on the yeast you use. A typical yeast-bread recipe calls for 2 teaspoons of instant yeast, or 2.5 of active dry. That difference, alone, is the high end of the suggested increase. Which would mean if you use instant yeast (which is 25% more active to begin with) you're covering that base.
I've never read any of her work. But I'm beginning to understand why she gets such mixed reviews among baking enthusiasts.
Question: Are you just quoting her? Or have you actually tried freezing dough, for various lengths of time, to see what happens?