Yep, that's sort of what I'm getting at too, I'm guessing that the're trying to avoid these being used inside, but under this porch, completely enclosed is rather a gray area, and the operative word being "in" as opposed to "on" may be the loophole...
But the question remains as to why?
-Virgil Residential/Commercial Inspector 5 Star Inspections Member IAEI
UL often has different protocols for residential and commercial/industrial constructions. I'm only guessing here, but I suspect that there is some concern about the largest allowed bulb making the fixture hot enough to pose a risk to easily ignitable materials. Solutions? Stonco doesnt' have a problem with their product. Use a smaller, or compact fluorescent bulb. Place where there are no drapes, etc., and there is plenty of ventilation around it.