His argument is that, while the facts are indeed true, steel doesn’t melt at the temperate felt within the Twin Towers, it’s structural rigidity is lessened significantly.
In short, steel doesn’t need to turn to liquid to lose it’s ability to remain structurally sound.
There are, of course, many arguments counter to the iron worker’s claims: the temperature that he heated the steel is unverifiable, the steel he used is significantly thinner than the steel in the towers, the length of time he heated the steel could very well have been longer than the short amount of times the towers burned, etc.
The stir this man has created, however, is significant. Check out the video below and make your own conclusions.
Source: IJ Review