I'm not against him joining the zombie side, however, I'm not a fan of the "I lost my memories and did something I wouldn't normally do" twist. I'd rather he joined their side for a rational reason. Maybe something like "I'll go with Tokiko and her so I can keep an eye on what the zombies are doing" or "if I copulate and join them, I can make sure my daughter and Mizuki are safe" or something. Doing a memory loss route feels kinda cheap to me.
Still though, I'm happy getting to see more Tokiko and this route will probably give even more of her. And more of Tsumugi.