thinking rationally...
if i stayed right there, yelled for help, and someone "rescued" me, i'd be at the spot where bigfoot was.
if he really did run off, and was no threat to me, i would be able to show tracks, and hopefully more proof of his existance. maybe he scuffed a tree and some fur can be found.
either way, unless i was in danger i would not leave the spot until it was documented, and someone else saw the proof, footprints or whatever.