Our friends were behind us and the guy who fell, and they took the boulders down after seeing what happened and not having spikes. They said it was scary and a lot of loose rocks... it isn't part of the trail, but they made it down to avoid that particular crossing. I don't see a way to avoid the ones at the top of the switchbacks.
I'm not experienced with snow enough to know how much longer it will be around. My guess is a couple weeks.
Also to note, the man who fell was not an inexperienced hiker. This was his 19th time doing Mt. Whitney.
