The thunderstorm that destroyed the aircraft was severe enough to tear a transport aircraft apart. Severe thunderstorms contain strong updrafts — columns of rapidly rising air — alongside their downdrafts. An updraft severe enough to contribute to structural failure of an aircraft is severe enough to significantly slow the descent of a seat assembly falling through it. The updraft hypothesis is plausible; whether it applies in her specific case cannot be confirmed.
The Amazon rainforest canopy is a genuinely complex structure rather than a flat barrier. In primary lowland Amazon forest, the canopy comprises multiple layers: emergent trees that can reach forty to fifty meters, a main canopy layer, an understory of smaller trees and large-leafed shrubs, and the ground-level vegetation layer. Each layer has some capacity to catch, slow, and redirect a falling object. A person falling through that layered structure encounters a series of impacts that distribute energy across time and space rather than concentrating it in a single instant. This is mechanically meaningful — the difference between stopping rapidly and stopping gradually is the difference between a force the body can absorb and one it cannot.
None of these factors, individually or in combination, is sufficient to guarantee survival. Most people who fall from aircraft at significant altitude do not survive. The factors that may have contributed to her survival were present; they were not sufficient on their own; and the specific configuration that made them act together in the way they did cannot be reproduced or fully analyzed. The fall that she survived is genuinely remarkable regardless of its mechanical explanation, and the mechanical explanation does not diminish that.