If there isn't enough life in the sandbed for the goby, it probably won't help, but it might make him more comfortable.
I read conflicting stuff on these guys, some say they need frequent feeding, others seem to say it's reasonably easy to care for. I don't know what the truth is, but I'd be nervous about getting one for a newish tank. They also seem to be fairly shy, but I hope the tankmates wouldn't bother it.
I'd definitely have the store feed him in front of you, if possible.