nope, awareness not nit-picking
- sorry, MJ bad choice of word!
As Cough says, Boeing (I think it is) have forbidden the use of the APU in this situation until the a/c has landed, and I suspect it was far from the Captain's mind at that stage to have yet another potential fire source start up.
Regarding radio selection - I'm not sure I could cope with that dilemma as well as everything else
IMO the Captain was 'between a rock and a hard place' with line-training and an 'unusual' failure.