I believe it has to do with filtering out harmonics associated with sampling the wave-form at up to 29ksps. The RC setup was recommended by the manufacturer, hence I followed their advice.
the Analog spec sheet shows a max input of +/-0.5V on the inputs
I prefer using an isolation transformer (which I'm modeling as an AC source), you can see the simplified bipolar circuit above. What I noticed though is that the setup I'm proposing will result in a common-mode voltage whereas the Analog spec sheet shows a max input of +/-0.5V on the inputs but is mum re: common-mode voltage. Does this mean I should simply ground one leg of the AC transformer and then follow in the footsteps of the Analog AC design (i.e. a 47kOhm drop-down resistor instead of 600kOhm given that the transformer output is about 9VACrms)? Or do you think my bipolar design will work?