Google switch Android to OpenJDK? Why?
Android is not Java-the-System. It uses Java-the-Language plus parts of Harmony to provide the standard basic Java types, collections, networking etc. libraries. Most everything else is Android specific, including the JVM.
IBM may have been Harmony members, but AFAIK they never shipped anything based on Harmony. Certainly the AIX JDK is completely Sun based. I would guess IBM regarded Harmony as insurance against Sun somehow taking their ball away.
So the Harmony project's goal of a complete Apache-licenced open source Java SE may be a little further away, but that's irrelevant to Google. They don't want or need Java SE. Or ME.