if he was bigger and hungry... and the RCS was slow to move away... yum yum. i watched a ghost shrimp take down another ghost shrimp IN THE BAG on the way back from the LFS (10-minute drive!). i started poking the bag to make him release the (still living) ghost shrimp, to no avail. it's not the first time i've seen this behavior either.
but if you keep them well-fed, it shouldn't be so bad to keep them together. just be mindful... any animal that can easily overpower and eat another will do just that. i think the decision process goes something like this: "I'm hungry. are you small enough to capture and eat without harming myself? yes? LUNCH!"