That is his passive defense, his scales are not his weapon.
King's wings are a direct part of his offensive fighting style, more akin to Kaido's claws than his base scales,
Also King is using hardening and a CROSS BLOCK against a 1vs1 attack, rather than not using hardening (or blocking) against an attack he is not focused on like Kaido did when he was focused on swallowing and killing Luffy...
When King can casually open his wings in tatsumaki rather than cross block at full power, not use his haki, and end up with only a single instantly regenerating scratch, then we'll talk.