Could be that way, Kaidou picks up King and King becomes his subordinate?
from what I understand
while it seems king's race was made extinct due to actions by celestial dragons (humans too)
it seems kaido's race might have had a bit of history in wano ( meaning in this case samurai are the ones responsible?)
with king I think kaido would have met both king and queen when he was held captive by the wg.