I had the following typed-up before Pino posted his latest . . .
Good points that got me thinking . . .
Possibility 1: Historically, the vehicle was too heavy for people just to carry it. The game mechanic as expressed in the Op Card could be to state that the Engineering squad functionally has an embedded (and invisible) Kettenkrad they use to get the Goliath to a point where they want to start using the wire-guided control. This would require just a bit of re-phrasing of the card but not the introduction of an entirely new unit (the prime mover). The limbering/un-limbering could just be reflected by the "spend 2 movement points" statement.
Possibility 2: Having to limber/un-limber the unit from a truck or half-track introduces game-mechanical considerations in terms of how a player would use it, requiring at least one action, possibly two, if we follow the standard ToI towing rules. Given the Goliath's limited movement, this would put the truck or half-track in danger. Would putting these vehicles in such danger be worth the effort to place the fragile, slow-moving Goliath anywhere near a location where the German player would have any chance of it being successful?
Possibility 3: It appears that this vehicle had an operational range of nearly a mile on-road, and about a half-mile off-road. Depends on the intended scale of a particular scenario, but maybe it's worth it just to allow the German player to place the unit directly on the map somewhere, and then send it off, one hex at a time, toward its destination (that is, do away with the Engineer squad having to place it, and with the truck/half-track towing).
Regarding Movement Points, I find myself leaning toward agreeing that the unit can move one hex at maximum, no matter what the terrain type is, except for swamps, rivers, ponds, lakes, etc. That would at least increase its potential utility in game terms.
Anyway, some initial thoughts!