He had underestimated the devastation caused by the Plane Destruction Bombs.
While Margareth had theoretically calculated the timing, damage, and range of the ensuing void, there was always a disparity between theory and reality. Initially, Alex had intended to swiftly blend into the Chaos fog and escape by teleportation, ensuring their safety from the disaster. But he hadn't anticipated the sheer power of the bombs, which proved to be far greater than expected. Before the teleportation process could complete, the Chaos fog was torn asunder by the relentless void storm, exposing their group, who had been relying on the fog for concealment. Left with no choice, they had to rely on their own legs and run for their lives. To stop now would mean certain death as they would be consumed by the void storm.