The media is deliberately hiding the issue of Cruz’ eligibility until Cruz becomes the candidate. Then they will bring it up repeatedly and leave doubts in the minds of the voters.
I have no doubt that they have this in mind should it become necessary. As things stand, there is a good chance Trump is going to get the nomination instead of Cruz. If that happens, they won't need to implement that plan.
If Cruz gets the nomination, then I fully expect the media to come out against him when it is too late to get someone else. They don't even have to win in court, they only have to keep putting out the rumor that his status is suspect, and it will hurt him in the polls.