I have a diamond sword enchanted with:
Looting III
Unbreaking III
Sharpness IV
Knockback II

When attacking a naturally spawned Iron Golem, the Iron Golem is not knocked back.
The Golem is taking the damage, only the knockback effect is affected.
Notes:
I've tested on a Zombie in the same world, the Zombie takes the knockback correctly, so seems Golem specific rather than sword specific.
I've not tested Snow Golems.
For completeness, the sword has also been named "Nemesis".