I'd call that the pin for a barrel-key lock.
In common usage here, at least, a spigot has to have something come out of it. This would be definition 2 in the Oxford English Dictionary: "A hollow wooden peg or tube used in drawing off a liquor; a faucet."
Earlier American dictionaries retain the understanding of a peg driven into a cask or barrel. The online American Heritage Dictionary defines spigot as:
1 A faucet.
2 A wooden faucet placed in the bunghole of a cask.
3 The vent plug of a cask.
In common usage, however, the meaning of a plug, spike, or pin has been lost on this side of the pond.