Doug,
I played professional golf , on the Nationwide Tour, before it was the title sponsor, and we played in some very hot conditions. I think the responsibility lies with the Tour to provide water on every hole for the players. Educate the players about the risks involved with heat exhaustion, the warning signs etc. After that, its up to the players to determine if they want to play in those conditions.
I also feel that the Tour should take extra care to provide shade and possibly misting tents ( similar to NFL and college football sidelines ) for spectators. I agree that it is really important to keep everyone hydrated ( maybe get a local sponsor to provide water to spectators with their local logo on the water bottle, win win for everyone ), but the show must go on.
I do have a 2 instances of heat stroke that I was privy to see. the Asian Tour, we played in January-March however many of the cities we played in are near the equator, Jakarta, Singapore, Kuala Lampur so it was particularly hot there during the winter months. During one of the events it was near 100 degrees and almost 100% humidity, it was really hot and sticky. One of the American players collapsed. This was back in mid 90's and while it was shocking, it didn't change the amount of water on the course over the next few days, and certainly wouldn't have been an acceptable reaction in the USA. So it can happen, I have certainly felt the effects of it, in Portland Oregon of all places, temperatures soared to around 100 degrees, I was near the lead of the the GI JOE/Thriftway event when I started to feel light headed and dizzy. I had to lay down a couple of times and played a 7 hole stretch, 4-5 over par. I think I shot 10 or so under for three rounds and finished in the top 5, so it was a killer stretch to my chances. I ended up getting to either a water or Gatorade on a tee, they were placed sporadically around the course, and immediately felt much better and finished the 2nd round strong with a couple of birdies. Serious indeed