The argument I've made against molten steel that seems to be the most effective (on pp. 84-85 of my
whitepaper) concerns the
quantity.
There are two competing theories: Either (a) there was only rare and incidental melting of steel at best, in which case we expect to find virtually no melted steel or iron, and what we find will be scattered or even microscopic; or (b) thermite or some other exceptional heat source was used, in which case we expect to find large volumes of melted steel or iron. Thermite, in particular, creates melted iron as part of its operation. The amounts of thermite the Truth Movement is speculating about are very large -- many tons of thermite, possibly hundreds of tons. We then expect to find either many tons of melted iron or virtually zero. There are no explanations for values in between.
Also, since the Truth Movement argues that
only this malicious event could melt iron, then after the thermite or whatever had done its job, the melted iron that resulted would solidify into puddles or slag-like blobs, and would remain so indefinitely. There is no way for the "ordinary" fire that followed to re-melt or otherwise disturb these objects.
Therefore, for the thermite theory to be correct, we must find huge blobs or very many moderate blobs of formerly melted iron or steel when we clean up the pile.
We find none. The best we can do is quote-mine a few individuals, none of whom performed any tests, and at least two of whom (Leslie Robertson and Mike Loizeaux) have later confirmed they were quoted inaccurately.
The Truth Movement fails to appreciate that there is no middle-ground because they never get around to proposing a complete hypothesis. This is one of the many errors that pervades their thinking.
I don't know if that will settle the argument for you, as it's likely that nothing can, but it should convince anyone who has the ability to learn.