The final option seems to be what's happened here. Presumably, there were a lot of bug reports of builds using OpenJDK a while ago and it was simply blacklisted as a simple solution. However that means that all new versions are been blocked, including 7 where OpenJDK is the reference implementation.
I can understand the motivation but for those of us working on the code, this kind of thing is quite annoying. It gives OpenJDK a bad press for an issue which may no longer be present and (to my knowledge as IcedTea maintainer and OpenJDK developer) has never been reported.
We do get a number of issues with the javac in OpenJDK 6 because it's some horrible hybrid which has changes that were made for 7 early on (so it's different from the proprietary 6 compiler) but not later fixes (so things that work with 7 don't work with it). On top of that, Oracle, having created this mess, don't seem prepared to support it to a great degree. However, this Android filter also blocks the 7 compiler which should be the same as the one in proprietary versions of 7.