Keeping Maya Khan's private life aside, i think what she was doing on the TV was transparent. What i have seen on TV was that she was invading couple's space in "public parks" not behind the doors. Her point about the whole episode was that parents do not have to blindly trust on their kids these days which is a dilemma in our society.
During all the action i saw few couples saving their back by running away from the camera and Maya Khan team didn't force them into questions. The program crew also didn't disclose the complete identity of the people interviewed. Now coming to the point whether she should have done it or not, everyone will have a different opinion due to the sensitivity of such issues in a Muslim society. I think her openly apologizing twice in front of the whole Sama TV audience was a good enough gesture for the people despising her as a TV show host.