What class is Mekkatorque?
First I am going to assume he is a class that players can be (and therefore, not a Tinker). Two things narrow down the class list right away. Clearly Mekkatorque wears plate, and his eyes do not glow blue, which leaves us with Warrior and Paladin.
Mekkatorque fights with a one handed mace, and shield. That fact would seem to run counter to Arms and Fury Warriors, and Holy and Retribution Paladins.
So he must protection spec’ed, either as a Warrior or Paladin.
Player gnomes can not be paladins, but NPCs seem to be able to skirt class restrictions. Lets call the fact that PC gnomes can’t be Paladins +1 for Warrior, and -1 for Paladin.
The Freethinker’s Plate Gelbin wears, and mace he wields give a bonus’ to intellect. In fact most armor from engineering or with armors that features moving gears on it gives intellect, like the Timepiece of the Bronze Flight. That’s +1 for Paladin. In addition to that maces are a part of the paladin kit. Gnomeregan has an ‘official’ sword in the Gnomeregan Bone Chopper. Many gnome NPC’s in New Tinkertown use it, but not Mekkatorque, +1/2 for paladin.
Mekkatorque also shoots lasers! Mekkatorque Ray is a beam of light that he shoots at Crushcog. The visual on Mekkatorque Missile is also a large flash of light. His third non-melee attack is a Goblin Dragon Gun, which come from engineering and not a class. Light based attacks +1 paladin.
Mekkatorque is always jolly. He laughs a lot! We never see any RAGE from him. -1 Warrior.
That brings the score to Warrior 0, Paladin 1.5
But math is boring and non-descriptiveness, so lets look at Mekkatorque’s story and see what we can find. My theory is that Mekkatorque has been either a Warrior or Tinker since the launch of the game. It fit with the gnome kit at the time, and there was not a lot of development for gnomes in Vanilla beyond The Grand Betrayal.
Then the Lich King invaded (Patch 3.0), and scourge zombies were roaming the streets of every major city on Azeroth. And in our fight against them, gnomes get this quest: http://wow.gamepedia.com/Quest:Ironforge_(gnome)
You receive an artifact of great power from a Naaru that you bring to Mekkatoque. Mekkatorque takes the concentrated light from you to make an artifact to destroy the undead. This is very similar to how the Ashbringer was made by Magni Bronzebeard. Magni was not a paladin, but he also did not use the Ashbringer, he gave it to a Paladin.
But does Gelbin give what he has created to the player to wield? No. He KEEPS it. I think that Gelbin Mekkatorque when presented with the raw power of Light directly from a Naaru, took that power and he kept it, used it create the mace he now carries (Which has a light bulb on top) and began transitioning to be a Paladin. It is at the END of the Lich King expansion (Patch 3.3) that Gelbin puts on his full set of Intellect plate and start wielding this new weapon.
My conclusion is that Gelbin Mekkatorque did not start as a Paladin, but that he is one now, and he is waiting until he is comfortable in his master of these powers before he begins to teach other gnomes this new discipline.