If Oda had every other major clan of Wano named after the moon and only Kurozumi clan named after charcoal for this stupid pun, I'll....I'll...I'll bitch about it here.
I think he did it too because charcoal is symbolically seen as evil too sometimes. Souls as dark as charcoal, if you've been bad, santa will give you coal, burning coals was language used by the Nazis I believe too and also Wano has been called Hell a few times in OP, Pluton is connected to Hades in mythogy and Hades is Hell/The underworld or the ruler/god of it or whatever and Kidd and Luffy said they are sending Big Mom and Kaido to Hell below IIRC?
There's definitely heavy symbolism going on here too. Cleansing by fire, purged of your sins by flames, burning in Hell, etc.
Ignoring the major issues with this arc, as Morj himself would say I believe and is a huge fan of, this arc has some very strong themes and symbolism.