I do not claim to know anything about ExoLab's legal infringement on Sun's trademarks. If ExoLab has crossed this line, then they are wrong.
However, if you are suggesting that Sun has some inherited right to naming because they created Java, I think you should find something worthwhile to write about.
In my opinion, Castor is accurately described as "Java Data Objects" and well represented by the JDO acronym. They explicitly indicate in their documentation and are very upfront that they are not compliant with the Sun JDO specification. If Sun wanted to carve out the name, they should have selected a more specific name than "Java Data Objects". This would be similar to Microsoft asking everyone with an xxxxx.net URL to change their domain name.
Perhaps it would be different if Castor was claiming to be a Sun JDO implementation. Their product is open source and they would gain nothing from this. I think you should move on to a more valuable topic.