I agree that a SAT of -60C can cause fuel to temps to drop below -37C.
But in that case you will get a warning, and if you follow the proper procedure, the fuel temp will not exceed -37C.
The proper procedure is to simply increase Mach or descend until you reach a TAT of -37C or greater. The SAT will still be well below -37C, but that doesn't matter because it is the TAT that will determine the fuel temp.
Lost in Saigon;
I will await the FDR report to see what procedure was followed. There are instances in the high Arctic where even Jet-B+ has "gelled" or "waxed" when the surface and operating flight level temperatures were lower than -50C. The only fuel that does not "freeze" is Diesel Fuel Arctic P-50. Of course it is "unapproved" for aviation use.