Although we could have a discussion wether the effect of the alleged kerosine (as you already know by now, I came to the conclusion long time ago there wasn't any) would really constitute a secondary effect of an airplane crash which they didn't consider instead of still be part of a primary consideration in the mimds of the designers, you still make a fair point here; nobody, no matter with how much expertise and good will can possibly foresee every aspect or all consequences of circumstances.
"The burning also doesn't need to be "furnace" level to affect steel strength; again we have plenty of evidence of a very prolonged period of burn due to smoke coming out. Kerosene burns at a max 1000C or so; you only need 400C for an hour or two to produce measurably strength loss"
The fact I agree with your theoretical assessment here is the exact reason why I must dismiss the official narrative, which - if you watch the following link - does not coincide with observed facts. You will see the head of NIST denying observed facts and evidence.