You are right, it is a reference to SC2's Thor, which might get scrapped (I mean from SC2), and ATM it isn't anymore the huge unit it was supposed to be (it just a goliath with a new look), which is quite sad

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There's info on this on PPM BTW.
The first version was made before the announcement of SC2. When the Thor came out, I figured it resembled my Leviathan (doubled dual railguns, big bipedal mech, and a similar structure), th main difference was the lack of artillery in my Leviathan and the lack of AA in the Thor. So I made a joke version (one with dual sonic cannons on the back; it's on PPM)
The first version of the Leviathan was useless and boring in gameplay (it also had an ugly shadow problem due to game limitations), you would be better massing Titans or Cerberus.
Just for fun, I tested the joke version, it was more useful and fun. Deploy and out range obelisks, destroy them; undeploy break havoc to everything else left, repeat if necessary. And it lived to the description of the unit; something that could take a base in it's own (it's an exaggeration BTW, it still has trouble with massed AT infantry). That way it replaced the original version.
Finally I tried to texture it, but he model was a mess, so I remade it (I added some "feedback" from the Thor, in it's memory, since it won't be like originally shown).