That whole fight scene is ridiculous. So you're telling me that a being with a power level in the billions can't one shot a group of people who's strength doesn't even equate to 1% of his?
King Cole's strength was inflated for two reasons:
1. To represent the capabilities of Frost Demons
2. Out of those inflated numbers, durability is his highest, so while he couldn't hurt Broly, he wouldn't get one shot