As far as I am aware regarding our rules, the only restriction on survivors actions regarding attacking the hive is they can not do so before the xenomorphs have had a chance to evolve into a Drone, which typically takes 60 seconds after round start.
Now, whether it makes sense strategically to place a hive in a very forward position just to deny survivors access to loot is an interesting question, but not a policy or rule one in my opinion, as it would fall into the same category as a hydro-hive, a high risk move.
Now, if this is a question of xenomorphs intentionally exploiting their OOC protection to prevent survivors from accessing meta-gear by intentionally placing the hivecore in a meta-spot before someone has had a chance to evolve into a Drone (which I suspect would be hard as you only have a 60 second window to do this and only the Queen could do this, who would at this stage basically be a 500hp Drone), then I would suggest sending an admin help as this might constitute a meta-gaming rule break.
This is my opinion however, not a management ruling.