While the statement looks seemingly correct, it has a big flaw.
There is no comparison between sex and dating.
Sex is a private act of pleasure only the person feels it (or not). (We are not going to voyeurism here)
A nun HAS to experience it to be able to say if she misses it or not, while people do not HAVE to experience dating to say they do not miss it.
Hence those who are answering they do not regret it are basing their answers from other people experiences.
Now for sex only, one could have used this statement if the question was:
“For those who never had sex, do you miss it?”
And if they had answered no, then this statement would have made some sense. 