I do not have those kinds of pests here up North either oddmar. I guess that if I was new to the area I would follow the wisdom of the Locals who have lived there all their lives and have experienced those problems 1st hand. Of course since I am sure that none of the Locals have ever actually built a straw bale building they could be mistaken,
If you get it sealed well with cob and plaster right down to the cement foundation there maybe no place for the pests to get in. Ants are pretty invasive though. I sounds like a gamble to try an untested method for your 1st build. How much would it add to the cost to follow what they suggest and elevate the shed? If the cost is too much more I might be more inclined to take the chance and try to build with out the extra cost. I am pretty cheap though,
You would hate to be penny wise and dollar foolish,
sorry that I can't be of more help. I am sure that my advise is worth exactly what you pay for it.
Never doubt that a small group of dedicated people can change the world, indeed it is the only thing that ever has.