While I am generally skeptical of this idea, 500km/hr winds occur at much higher altitudes - the force is much less than it seems because there is much less air doing the pushing. If a human can get to the edge of space and freefall safely, I imagine that will not be the sticking point.
They are proposing a fabric chimney. For sure that has its own challenges, but shear force isn't as much a problem, from I would intuit the setup to be.
