The reason that nobody bothers to grasp this concept is that it's irrelevant.
Let's try framing your argument in logical terms.
P1: Molten steel was observed weeks after the collapse.
P2: No process other than the thermite reaction is capable of producing molten steel.[in the 3 towers]
C1: Therefore, a thermite reaction was present prior to the collapse.
We are disputing P2, so you need a line of argument that supports it. At present your line of argument is:
P3: Thermite is capable of producing molten steel.
P4: I know of no other process capable of producing molten steel.
C2: Therefore, no process other than the thermite reaction is capable of producing molten steel.
C2 is automatically invalid,