It's a shame you can't give him a webway portal.
I think Haemy's main strength lies in giving his unit +1 on the PfP table. If you keep him and his unit reserved, they're guaranteed to arrive with at least FNP (5+) which is as good as their FNP gets in Codex: DE anyway.
Makes them a bit more versatile and survivable, at least. You said warriors - can that stretch to upgrading them to Trueborn? You might be cool with some splintercannon trueborn, holding an objective in cover, haemy with a 10pt hexrifle so they all have that 36" range. It'll punish any infantry that want to have a go, command type squads included. Don't forget the precision shots. If points allow, give them a splinter rack raider so they can do some damage while they get around, and keep them in reserve.
I dunno, there's certainly better things you could do, but I'll leave those to better players to think of. I reckon I could make this idea work, anyway, so I'd hope you can too.
Dark Angels. The Rock. Lion El "Dwayne" Jonson. I can't be the first person to have thought of this.