For one, the question was merely whether we'd observe an increased birth rate, not whether that is a reason to pass such a law.
Secondly, you're the one who's bringing up coercion. You can both not be on social media and not have kids. It's still your decision.
The reason for it might not have been made explicit but we both understand what they were driving at and why they weren't "merely" asking the question of what effect a social media ban might have on chocolate sales or something equally arbitrary.
