It is confusing! But it also is accurate in a way. LOD 0 is the most complex (most triangles), and the highest number LOD is the most simplified. So the effect of this setting is to limit how complex the mesh is allowed to be. As the long description says, if you put 2 as the default, the engine will be allowed to use LOD 2, LOD 3, 4, etc, but not 0 or 1. So by using this control to set a lower limit on the LOD number that can be chosen, you’re effectively limiting the maximum complexity of the mesh. That’s what the tooltip means when it says “does not go below” – the LOD number the engine selects won’t “go below” the LOD number you choose.
Like, you’re setting the minimum LOD level, you’re not setting the minimum mesh complexity. You’re setting the maximum complexity by setting the minimum LOD level.
I agree the tooltip could be rewritten for clarity.