Bryan,
Just finished up half dome on Tuesday this week. I can report back that the JMT section was open and clear. We hiked down that way on the way down.
Like others have stated, there were plenty of others on the trail. You will not be alone for very long. If she can make it to the top of Nevada falls, it's a mile or so of flat easy terrain. She can then hang out near the Merced river by the backpackers camp where there are bathrooms and other hikers. Heck, the top of Nevada falls has some of the most scenic resting spots on the trail. I wouldn't mind hanging around that area for half the day.
Have fun!
Cody
