Summary:
Blast Protection does not reduce explosion knockback in creative game mode.
Since the player receives knockback in creative mode, it would make sense that Blast Protection also works in creative mode.

Steps to reproduce:

1. Switch to creative game mode.
2. Give yourself armor with Blast Protection 4:

   /give @s netherite_helmet{Enchantments:[{id:"minecraft:blast_protection",lvl:4s}]} 1

3. Stand next to the exploding creeper/TNT.

Observed results:
Blast Protection does not reduce explosion knockback in creative game mode.

Expected results:
Blast Protection reduce explosion knockback in creative game mode.