Hi Miff
I am not a sports physio so someone more knowledgeable may comment.
However as a treatment it seems a bit extreme. While immobilistation maybe counterproductive with most injuries, this sounds going a bit far.
Here is one interesting study that compared stretching and strengthening and Icing for acute hamstrings vs trunk stabilisation, progressive agility and icing. Interestingly the second group did better long term than the localised hamstring stretching and strengthening, with faster resumption of sport and less reinjury.
PEDro - Detailed Search Results