Free platform

The GPLv2 does bound Oracle. Namely, it can not rescind the permissions it gave to others as part of a software license. This is basic legal theory, you can not tell others “you can do foo, if bar” then change your mind once others have expended resources reaching bar (at least, not in a legal document). Otherwise, no license would be worth the words used in it.

The only thing Oracle can do is define new conditions for new software releases, or relax conditions on old software releases. They are not allowed to add restrictions on old software releases people already licensed under specific terms (and the GPL is worded in such a way the license can be transmitted from user to user and from version to derivatives).