It's possible in C11th the people writing the treatise weren't in the birthing room, or that this practice was done (i know in C11th Ireland the treament for overlong tendons in horses front legs as to burn the backs (pin-firing, still known of) and then put sheeps dung into the open burns to "promote contraction" of the tissues, amazingly few animals diedof this!). It isn't done anymore. Babies can certainly turn of their own accord during labour, but i cannot see when the feet are already out that there'd be room for a baby to turn even if you managed to wedge the feet back in.
Is it possible there was a political motivation for the treatise? Like to make the point that their attendants had solved a dangerous problem which was known to be risky, or other self-promotion of some kind? I LOED reading the Irish and Welsh legal and medical texts from the same period during my degree, you find some incredible wisdom and some amazing craziness side by side! :)