The screenshot shows reward for sharing, which isn't covered by that.
Based on the screenshot, you're doing the Like rewarding in the non-compliant manner, not the compliant one - doesn't appear that pre-existing likes get the 10 entries.
Personal experience. The company I work for puts together online sweeps/contests including Facebook ones, and we've had a couple clients come to us after getting their promotions shut down for violating guidelines.
Enforcement seems to be random to the point where I'm pretty sure it only happens if someone reports a page or someone from Facebook stumbles upon it, but it can happen.
We are compliant with this.