It appears that LJ has made himself a stand using table like construction. A table only needs to be as strong as the load it carries. The fact that the stand elevates the hives it is unlikely he will have any trouble with weight because he won't let the hive get out of reach. So yes there are stronger geometries that will perform better but it doesn't have to.
Now on the discussion of out gassing methyl bromide from the pallets there must be a safety standard already in place or you would not be allowed to bring them into a building. I am not a chemist, far from it but I do know there are meters that measure out-gassing of plastic parts or the sterilization of parts by ETO method. It doesn't seem as though you would have to put bees in a box to prove the out-gassing of methyl bromide after so many days of treatment.
All my hives are on pallets and I don't know or care if they have been treated. The bees have no problem crawling all over them.