The article left off part of part of what the court said, which was (emphasis added):
> Rather, the remedy for Plaintiffs’ injuries lies in pursuing tort claims, electing representatives who will better manage the public-water system, and petitioning their representatives for other remedies.
Suing the government is indeed one of the things the court said they could do. They just can't sue alleging a violation of the particular federal statute they used in this suit.
At most that will just get it dismissed against some individual plaintiffs. It won't affect their case against the city and any companies such as the engineering firm that was a defendant in this particular lawsuit.
It'll come out of their taxes, which the city will either have to raise, or cut costs somewhere to pay for. The people responsible will be neither criminally nor civilly liable, leaving zero disincentive to others.
If the engineering firm is acting as an 'agent of the state' then the protections extend to them as well. Otherwise we wouldn't be able to protect private prisons, etc from being sued, and we can't have that happening in America. So the court invented a fake protection (qualified immunity), and then invented a fake protected class called 'agents of the state'.
Is suing the government not essentially a petition for remedies? How else do you get the gov to listen?