To answer your original question on how to protect against such moves -
Zee and Dewan promoters did not score high on corporate governance and this was well known in investing circles. Even RJ claimed in one interview that he invested in Dewan even though markets had doubt about the company. So Avoid such promoter groups. Avoid concentrated portfolio. Avoid companies where promoters have high pledges.
Checklist does not allow me to invest in media and education stocks so Zee companies would be out. Plus they figure along with Dewan in the list of promoter groups to avoid.