Dude you have no idea what you're talking about. Literally just pulling stuff out of your behind. Scale has absolutely nothing to do with how the unit is represented.
Look at SC1, unit scale was way off:
SCVs the size of Vultures and Wraiths. Production buildings with looks so squished and disproportionate.
Carriers barely any larger than Dragoons. Archons nearly the same size.
Reaver - supposedly a mobile factory looks tiny.
Scale isn't anything in the game. It is meaningless. Thor is large because they originally envisioned it to be. But playtesting showed it isn't fun to have large objects in the game. The unit looks pretty good resized.
What is your problem anyway? Robot fetish?