Unfortunately nems move at their own will and you can't really put them where YOU want, they kinda go where they get what they are looking for whether it be light, flow or whatever. Is he really attached to that rock? A slight nudge might make him rethink his position but you def don't wanna forcefully move him or you risk damaging him.
180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18