There are many other problems with this explanation, including:
Oliver Smart has posted a typical bond angle vs. molecular potential energy curve as part of an online course on protein structure. He makes a quick estimate of the size of bond angle deviations from their equilibrium values for a particular temperature, using the equipartition theorem. While the estimate isn't terribly accurate, it's easy to see that typical bond angles aren't going open up during vibrations much more at 373 K than they do at 273 K.
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