From the source code:
So, obviously not meant to be called from a script, and certainly not from Python, since plugins called by Python always have the GIMP_RUN_NONINTERACTIVE flag set. You may have some luck calling from Scripts-fu since IIRC in Script-fu you can set the interactive flag (but the user will get a dialog...).
Code:
case GIMP_RUN_INTERACTIVE:
/* Possibly retrieve data */
gimp_get_data (PLUG_IN_PROC, &qbist_info);
/* Get information from the dialog */
if (dialog_run ())
{
status = GIMP_PDB_SUCCESS;
gimp_set_data (PLUG_IN_PROC, &qbist_info, sizeof (QbistInfo));
}
else
status = GIMP_PDB_EXECUTION_ERROR;
break;
case GIMP_RUN_NONINTERACTIVE:
status = GIMP_PDB_CALLING_ERROR;
break;