As someone that has actually taken the shortcut in question, I would urge you not to do it. It was before I knew as much as I know now, but even then I knew it wasn't an awesome thing to do. I was with a friend doing an out and back to Isolation via Glen Boulder, and we were wrecked from a Kinsman traverse the day before. We basically just ran out of gas and weren't excited about the trip up to BS. We got to a place on Davis where we scouted for cairns on Glen Boulder, found them, and then tried to locate a rock-hop route. We thought we had a good one, but basically, as others have mentioned, the rocks aren't great for it, and three-fourths of the way through we basically had to take big strides through some of the spongey fragile stuff. I can still feel it under my boots, and we almost surely killed some of it. I still feel awful about it and I still think about almost every time I'm above treeline. Worse yet, we maybe saved 20 minutes maximum on what was a very long day anyway. I just don't think it's worth it.
On another note, I also generally agree with Wu. But there are some places where it's nearly impossible NOT to step on green stuff above treeline. The Castle trail above treeline on Jefferson strikes me as one such place where alpine grass exists directly on the trail and is at some points really hard to avoid without being fanatical.