i would assume, with the mention of weight, that they wish to move the tank elsewhere but do not want a collapsing burrow.
dig him out with a spoon or try to block off his retreat when he is at the surface somehow, then just remove him and let him go and sort out any cave ins when you have moved it.
i suggest half a tube up against the side of the glass going half way down into the sand. this way he can go down here and be visible but also carry on digging his burrow further, but no matter how elaborate it is, he will still wait for food where you can see him and check everything is fine.