BPs do not need uv rays at all. They are nocturnal ground dwellers. They get no benefits from uv rays at all. Most keepers don't even put a light on BP enclosures because this will just cause it to stay hidden more.
All they need is the natural cycle of day and night as the light shows through your windows. Really they only need this for breeding purposes but even then it's been proven that light cycles play a far less role in breeding than the natural barometric pressure changes if the seasons anyway..
That person is going by old fashioned info where everyone thought that all reptiles need sunlight. This is not true at all.
You were right, they don't need UVB lighting at all. My snakes have no lighting whatsoever apart from when I turn the lights on in the room or when I have the blinds open in the day, and they're all doing just fine. All the light will do is kill your humidity.
1.0 Normal - Maynard
1.0 POG - Victor
0.1 YB - Diana