While I expect we all agree moving ash from an infested area to a non, or lightly invested area is clearly a bad idea to be avoided, as well as illegal, if you are transporting ash into an infested area the risk of spreading borers is trivial.
I suggest reading the NFS article and the supporting research below. In short, they have found double bagging in contractor grade bags tightly sealed and left for several weeks will kill the borers. The research is to provide suggestions for how to store and dispose of confiscated firewood, but it seems it would apply here as well.
Of course the best response is to only use locally sourced ash.