If you have a sump, you can grow him out down there. Things that might be a problem can have useful lives cleaning the sump.
In a tank there’s always a chance the good become bad
Example, red leg hermits are supposed to be safe....NOT....had only attack and kill a clownfish, all crabs are opportunistic and will attack the slow, not moving, sick or dead
Since I removed every crab and hitchhiker, I have not lost a fish, coral or snail
Always assume bad in crabs.
Grump would like to be friends....
What if that one is grumpier?