Lunars, Liminals, Alchemicals, Infernals, and presumably any given random Exigent you might want to make where this actually fits its themes have ways of turning giant. They are notably not identical ways. Janest's Essence writeup lets her turn giant as a Paul Bunyan reference.
At the same time, Dragon-Blooded, Getimians, Solars, Abyssals and Sidereals cannot turn giant with their own charms that we know of. Why is it important that this one variety of Exigent that is given their powers to defend a city should be able to turn into a Kaiju, when that isn't any more thematic for them than it is for the half of the Exalt types who just don't get charms like that?
My strongest, gut level response to the argument that an Architect should have to smash up their own city in order to use their high essence charms is just "fuck that". Don't make them mechanically bad at their job just because knocking over a building would theoretically be cool.