The problem with a text this opaque and vague is that it is very open to interpretation, and the danger of reading things
into vague texts instead of
from them cannot be overstated.
Lacking circumstantial evidence on the issue, all remains idle speculation and an amusing pastime at best, but nothing meaningful can be said. The case for the wizard of oz to be intended as a political commentary hinges a bit too much on coincidence and liberal interpretation for my taste, especially what with Baum commenting
himself that he did not intend it as a political metaphor.
Of course it is very possible that any given vague text was meant as a satire, or roman a clef, and understood as such by the contemporary readers of its epoch, but at this remove this cannot be asserted without additional evidence.
P.S.:
Another speculation is that she represents Theodore Roosevelt, the United States president. Some people believe this theory more than the other because of the similarities in the names. (Think: Dor-o-thy and The-o-dore).
HEH.