In gnupg/tools/gpgconf.c, we have lines like:
{ aListComponents, "list-components", 256, N_("list all components") },
Here, we use the value 256 for the flag. When it was written in 2004, the value didn't have valid semantics in argsparse.
IIUC, it is a simple mistake and the correct value is 128 (ARGPARSE_OPT_COMMAND)
Currently, 256 has different semantics as ARGPARSE_OPT_CONFFILE.