Sorry to tell you--they effectively ARE an agent of the government.
They are citizens, no more, no less. The Government is not a party to such a lawsuit and has no interest in its outcome.
Once the outcome is in place, the government has an interest. The government DOES have an interest in preventing said outcomes from being too onerous--it might inspire the pursuit of some more...primitive...forms of "justice" by various interested parties to the case.
The citizens of the State of Utah have cast judgment against the actions of the company, under the laws of Utah, and that decision is enforced by the laws of Utah. Today's Supreme Court decision undercuts the sovereignty of both state law and the jury system.
Well, if you're putting it that way...
What is to keep the jury from imposing as punishment the mandatory dismemberment of the company's officers and their families at a Monster Truck Rally?
Oh, you mean that they aren't THAT sovereign?
Whoopsie.
Maybe they never were as sovereign as you think they are.
And kindly note your construction--you describe them as "the citizens of the State of Utah." Go read a criminal indictment; it will say "The People of Utah vs. XXX."
Semantically, you just made civil and criminal cases co-equal under the Eighth Amendment.