Last fight I had with momentus one or two enraged zombies got in the mix. not sure that he spawned them, but if not it is quite a coincidence. I am assuming he spawns a couple enraged zombies too. someone correct me if they factually know this to be false.
I have 4 of them, they all say Guardian. Momentus does seem to spit out Enraged Zombies as well so maybe thats what you got. The guardians also don't 'cure' right away (for me anyways). I had to wait like 5 minutes for it to turn. The enraged villager zombies were instant.
When the right kind of zombie is spawned (must be a villager looking zombie), you corner it; make sure it's blocked from the sun, throw a potion of weakness at him and right click him with a golden apple. He will begin to shake then about 5 mins later, turns in to a villager and you egg him. Because it was named already, it's keeps it's name of Enraged Gaurdian/Zombie. Here's a vid: https://www.youtube.com/watch?v=D2lmytxeHn8
