Yes but we already know that Shards can connect to each other via their Hosts; that's the basis of several Parahuman Weirdness things.It would still need to work with the other Shard as to not kill their Host in the struggle to take control of something directly connected to the Host's brain. For the comparison it kinda ignores the whole idea that Zion and Eden would have administrator access to all the Shards because they sent them out in the first place while the other two wouldn't.
Also I'm pretty sure that Administrator Access is one of the things that the Entities give away at the end of the start of every Cycle.