Ocean monuments ignore sea level

What I expected to happen was...:
I was hoping to find a completely empty and unsurrounded-by-water ocean monument if I set the sea level to 1.

What actually happened was...:
I created a "Customized" map, setting the sea level to one and the biome to Deep Ocean only to make it easier to find an ocean monument. However, the ocean around the monument, unlike the rest of the ocean, was still there.

Steps to Reproduce:
1. Create a "Customized" world.
2. Set the sea level to "1"
3. Set the biome to 'deep ocean' only. This might not be a necessary step, but makes it easier to find the bug!