The Bison had a better chance to outrun the Bear on the pavement. In the brush the Bear will win. But the poor Bison was so nadly burned, the winter would have frozen him anyway so the Bear just got fresh rather than frozen.
The bison escaped, but the rangers capped him later:
"Wypiszinski says once in the safety of the woods the bison out maneuvered the grizzly, escaping to live exactly one more day. Park rangers had to put the bison down due to the injuries it sustained.