[reverseapachemaster]

Am I correct in thinking the purpose of sauergut is to remove O2?  Or is it intended as a pH adjustment?

It is a pH adjustment. It is the result of a lacto fermentation,  which are generally anerobic, so they arent utilizing O2.  O2 in one of those fermentations can allow other organisms to take off and give undesired  odors and flavors.

If using crushed grain as an inoculant you would almost certainly get some yeast and other critters that ferment aerobically. Even at low acid rest temperatures it is improbable that the aerobic fermenting organisms would have sufficient time for something in the mash to break down starches to sugar and ferment them before you raised the temperature to the next rest. You would have to add a simple sugar source and hope what you added plus whatever is on the grain doesn't produce any undesirable flavors. 

[MDL]

Am I correct in thinking the purpose of sauergut is to remove O2?  Or is it intended as a pH adjustment?

It is a pH adjustment. It is the result of a lacto fermentation,  which are generally anerobic, so they arent utilizing O2.  O2 in one of those fermentations can allow other organisms to take off and give undesired  odors and flavors.

If using crushed grain as an inoculant you would almost certainly get some yeast and other critters that ferment aerobically. Even at low acid rest temperatures it is improbable that the aerobic fermenting organisms would have sufficient time for something in the mash to break down starches to sugar and ferment them before you raised the temperature to the next rest. You would have to add a simple sugar source and hope what you added plus whatever is on the grain doesn't produce any undesirable flavors.

The instructions for culturing sauergut from grain are to incubate at 118F. I think the elevated temp is to discourage wild yeast growth and favor lactobacillus, specifically amyloliticus.