Disneyworld in Orlando Florida with an average summer temperature of 91F responds to dozens of heat stroke cases with people wearing shorts and shirts, merely walking around and waiting in lines to enjoy rides.
Yeah, there's a wide variation in training, condition, and the level of care/equipment/hydration, and the results (and there are lots of heat injuries in the military, too). The OSHA limits are clearly not the limits of human performance (either low or high). One of the things is you acclimate to it over a period of a week or two fairly successfully, so if there were a datacenter which constantly operated in that range, you should be able to get staff who can handle it. (I'm sure steel mills and other industrial facilities have high temperatures, too).
