--introspect-cli follows the same deferred pattern as --help: parse_argv()
only records the action, and it is executed in the same place where
ACTION_HELP and ACTION_VERSION are handled.
The help is looked up by explicit name: in the multicall configuration
the systemd and systemd-executor commands share one binary, so the
"first COMMAND" default would depend on link order.
The "This program takes no positional arguments." line is dropped from
the help output — the default "[OPTION…]" synopsis already says so.
(And also, this is not quite true. It does take positional args when
called as init.)