Good distillers use a double boil to eliminate any gas accumulation! And often come with water purifiers for the timid! However a few molecules of gases is not a factor! Distilling eliminates the heavy insoluables and the pathogens to 99.99% pure something no filter can claim!
So once again the use of the fear factor is overstated and as usual not beneficial for those seeking good health!
If one is FEARful of the small amount of metal from a stainless steel pot one I imagine would have a glass or ceramic pot on hand already for boiling regular foods!
A little bit of common sense goes a long way! I myself am not FEARful of the little bit of co2 absorbed in the water as I said this is a gas that is very easily neutralized by many ways including a pinch of bicarb or magnesium ! I beleive the saliva will take care of this small amount of co2 anyway although I dont see it as critical or worth frightening people over it! The long term testimony of many proves this!