How bad is this fire damaged alloy frame?
I've done a bit of aluminum anodizing which requires annealing (softening) of the metal. This happens at about 650F. You mentioned the drop bars being melted so I suspect the top tube is likely annealed and won't have the same stiffness as it's suppose to. It may flex more than it should and may cause other parts to flex more also.

The head tube bearings were also mentioned and should be checked. I also wouldn't trust the seat post.