What resistor values should I use for a voltage divider that has to operate at low temperatures?
The statements in the datasheet do not seem to be related as you appear to have assumed. Leakage paths are not associated with low temperatures, there are two separate issues. Edit: Noted that the OP quoted a different section of the datasheet which appears (to me) to be wrong. 

At lower temperatures, the gain of BJTs will drop so the error due to bias currents will be higher, hence you should use lower value resistors for the same accuracy level. The feedback bias current is typically 10nA at 25°C, which is consistent with a BJT input.  

It's not clear from the datasheet what the internal circuitry is- but the 1.23V implies a bipolar bandgap reference and they may have a BJT-input differential amplifier for the error amplifier- they say transconductance type, which is typically bipolar input.  

Actual datasheet text: 



This is really a common issue when you are designing products that have to operate over a wide temperature range- some things tend to deteriorate at low temperatures, and some at high temperatures (and many things get worse with radiation, but that's another story).