Hello Ramanan,
That's right, it is possible to exclude the Age range and Gender AdGroup criterion. There have been several changes to the AdWords API services and the current Criteria Usage table is not up-to-date. I have shared this with the team. Meanwhile, we recommend that you test each criteria that you want to target or exclude.
Let me know if you have any other questions.
Regards,
Bharani, AdWords API Team