I'm not privy to Google's management thinking but I suspect they made that decision to save time and hit a market window. Android originally used the open source Apache Harmony Java implementation which didn't comply with the Sun (Oracle) Java license for the TCK. If Google had dropped Harmony they would have had to either write their own Java implementation from scratch or license one from another vendor like IBM. They had plenty of resources to pursue those other options but either one would have take more time and allowed Apple to build a lead in the smartphone market. So Google stuck with Harmony and now they're facing the legal consequences.