As someone who works very prominently in mobile device security, and had to long ago come to the realization that I actually KNEW the people who could manage to hack into my phones... I agree with your answer 100%. The threat analysis here leading to only using Firefox on your desktop computer to access your bank makes absolutely no sense to me and--to inject some conspiracy theory back into this (for shits and giggles)--almost feels like "what the enemy wants you to do" ;P.