The tuples in the list for GE version detection (game/oblivion/__init__.py lines 76-78)

exe = [(u'Data',u'obse',u'plugins',u'obge.dll'),
       (u'Data',u'obse',u'plugins',u'obgev2.dll'),
       ]

contain 'Data' as part of the path, but in belt.py these get joined with [bass.dirs['mods'] which itself represents the 'Data' folder. As a result the files are not found, so GE detection for CompareGEVersion and RequireVersions doesn't work. Removing 'Data' from the paths fixes the issue.

On a related note, maybe the plugin for Oblivion Reloaded (obse/plugins/OblivionReloaded.dll) could be added to the list since it is the current "incarnation" of OBGE. I tested this and the version is correctly detected as '7.0.0.0'.