Yes, your hunter is MM.
Serpent Spread contributes to a huge amount of damage. That, and lower trap CD means more frost traps he can fling at oozes (and more fire traps on adds). Notice my friend's kill has the hunter as MM, but keep in mind that we're trying to squeeze out every bit of DPS we can here to get you the kill. He's definitely going to kill adds faster, imo, as Survival. And the faster you kill adds, the more DPS you can spare for legs, which might be what can push you over the edge to get him to transition before Superheated.
Every bit adds up.
Oh: also keep in mind survival and MM gear about the same from what I understand from EJ and other sources, so tell him not to worry about that. Even if the gear is suboptimal, I firmly believe your hunter will be doing way better on this particular fight as Survival.