The burning jumper scenario isn’t quite the same. In the case of 9/11 twin towers, the jumpers were murdered, they didn’t commit suicide. Death was certain for them whether they had jumped or not.
It's an example which people can understand. It's an impossible situation to escape from. They chose the slightly better scenario. People who commit suicide also chose the slightly better scenario (in their mind) for them.
They're not the same. In the jumper scenario, imminent death was certain whether they jumped or not. This is only true in a small fraction of suicides.