Have the same opinion as TPJ. The forecast for Wednesday was for thunderstorms am. Even with an "Alpine start" it would have been tough to get off prior to this, but Exum did. The push for the summit is an alluring thing, but someone has to be the leader and be able to make the appropriate (correct) choices. Yes the T-storms were huge. 60 mph winds, 1/4" hail, numerous lightning strikes.
But, all one has to do is look around and you could see this coming. The O-S route (the route they were on) in not hidden, is fairly exposed, and you can see to the SW for miles (which is were the majority of the T-storms come from). They don't just "creep up on you".
Per the news they were around the Belly Roll. I know that there are several/numerous cracks one can wedge themselves into and "hunker down" in around (above/below) that feature. Hopefully they tried to do that and weren't climbing on.
My condolences to the familes of both the climbers - there was a female that died on Tuesday coming off of the Middle Teton (got lost coming down from the summit?), and then the climber in this group of 17 that fell 2000'. Stories state that he was roped in and had a harness on, yet he fell. Not sure if his rope burned through or if the protection was on correctly.
Yesterday afternoon, park rangers had to rescue another climber off the Grand.