If the 100 L and the 135 and all the nikons survive the heat, then this will too. "Shameless marketing" is much easier to believe.
Yup, the "big whites" are supposedly painted that way so that excess heat does not cause the fluorite elements to expand, but on a lens like this it's purely marketing.
The 100/2.8L Macro IS and 135/2L do not have any fluorite elements, but the 70-200/2.8L IS II does have a fluorite element.
BTW, it's not about 'survival' - no one (at least, not me) is suggesting a little sunshine will cause a fluorite element to crack. It's about functionality - if the increased heat causes an element to expand beyond design tolerances, IQ will likely suffer.