I love my yellow watchman gobies...they are a hoot. I got both gobies at the same time, from the same tank at lfs, both share the same cave and appear to be quite happy together. I later purchaseda pistol shrimp but neither goby shares space with the
shrimp...they won't leave their cave.
I then purchased a high fin banded goby and it wouldn't have anything to do with the pistol shrimp either!
My pistol shrimp dug his own space out of the ls. I make sure he gets fed. He snaps his claw at me..he (has to be a he) thinks he is one big, bad dude.
Good luck...I hope you have success when you get your shrimp & goby.