They don't want people who interact with the baby to do that "pretty girl/ big strong boy" stuff that has been well documented in the past, and say that if nobody knows whether Anush is a boy or a girl they won't have that automatic bias to treat them differently.
Several things will happen though, because we really can't control what others do (much as we might like to)
-many people will make assumptions about the child's sex and the older the child is, the more likely it is that the assumptions are correct
-people will also make assumptions about the parents and this kind of controlling behaviour is not conducive to good social interactions
- there are also numerous trust issues in play, but if they keep this up after the age of eight, the age when children get single-sex facilities, the rights and needs of other children may be negatively impacted by this child
-from what I've seen, not a few kids in this kind of situation eventually rebel against their parents and end up resenting them for marginalising them like that
If you want to resist the insidious consequences of gender stereotyping, you teach your children from a very young age that apart from very few biological functions, your sex does not dictate what you do, wear, play with or like. And the older you get, the more you teach them about that. In the meantime, you parent accordingly.
One does not defeat an enemy by pretending it doesn't exist, but by facing up to it, learning all about it and then taking it on.