Your friend sounds a little immature, hobos have quite a history and one made his way to the Supreme Court, William Douglas. Many Civil War, WW1, WW2, Korea, Viet Nam, and most likely our current vets have found this life of traveling and comradely particularly agreeable to them after seeing the horrors of war. A little empathy on his part would be in order. Too bad he sees the value of a knife in its stabbing potential.
Your job as a friend is to call him out and re educate him on the most valuable tool ever created, good luck !