There is some discussion on the noose knot page that indicates the hangman's knot is deliberately not included in the encyclopedia. The site doesn't give a reason for not including it.
I agree it should be included in an encyclopedia of knots. Any knot can be dangerous if you put it around your neck.
The site also has the noose knot which can be extended to create a hangman's knot: https://www.animatedknots.com/noose-knot
There is some discussion on the noose knot page that indicates the hangman's knot is deliberately not included in the encyclopedia. The site doesn't give a reason for not including it.
I agree it should be included in an encyclopedia of knots. Any knot can be dangerous if you put it around your neck.