Maybe it's because it's religious and some people, rather than being just atheists, are anti-religion. Some people are also against order and "traditions" (anything that wasn't made up during the last 100 years). If it was about her being forced to wear it, why would he be bothering her?
We have been here before, you have been unable to show where it is stated in the Qur'an that women must cover their faces. It is not a religious requirement.
It is a personal preference foe some muslim moment, it is a requirement dictated by the husband for other muslim women