The head of the Ork model is a large target, and it's in the (I'll use several quotes from another person here.) center mass (Body) of the ork, and takes up approximately a quarter of the center mass, and it's in the upper body area, where weapons will usually shoot there due to recoil. Meaning, 25%ish of the time, Orks are headshotted.

So, reduce the damage done on headshots to Orks. Don't nullify the multiplier entirely, but weaken it. Orks in the lore are able to take that kind of abuse to the head without too many problems, due to their skeletal structure and composition of their body.

I believe the headshot hitbox for Orks is either A. bugged or B. larger than intended and it's supposed to get changed in a future hotfix/patch.

Alternatively, they could change the ork movement animation to jave more of a loping, swaying quality. Pretty hard to hit a headshot when the target is swaying side to side while the ork is running at the target.

Brent Ellison already addressed this in the last twitch stream, he said they were going to reduce the side of the hitbox because Orks get hit the most.

They were going to do this before immediately jumping on giving them more toughness, etc.