Technically those aren't kobolds but Diggers, a lower ranked but similar race. I thought of them like a starter race for a younger Volcano Dragon. Retanlong's retinue is a lot more advanced and they do not play around. Neither, apparently, does Retanlong.
Which makes Suzocon-kyo crashing his party a truly ballsy move, but that's a kitsune for you. They're always poking their noses where they don't belong.