You asked whether it was "true or movie fiction". It doesn;t seem practical to me for anyone to carry a knife in the wilderness inverted like that. A belt sheath, or rather a conventional carry sheath is practical.

To their detriment, they didn't consult with me before filming that movie. Had they done so, in addition to recommending a traditional carry sheath, I would also have recommended to the producers that he shave with a Gillette disposable razor, and that they leave the bowie blade for chopping "stuff" up.