The problem is, you'll never get to establish a sale price if the seller thinks his house is worth 100k over market or a buyer thinks the seller is asking 100k over market because that's what they saw on Zillow.
Further, when zillow gets the estimate of a house wrong it costs them nothing, but there are real costs to Zillow's bad estimates to buyers and sellers.
If Zillow gets the estimate wrong, then people will stop using their estimates, costing them in reputation and perhaps dollars down the line.
There are so many sources of info for house value that I don't see how Zillow could single handedly be manipulating a house's sale price. If it's not selling for what the homeowner thinks it's worth, it's probably not worth that much.
A "civil matter" is where the courts—a part of government—apply law—created by government—to non-crimes disputes, often (as in this case) between private parties.
It absolutely does not indicate the absence of government involvement, even if the government isn't a party to the litigation.
The problem is, you'll never get to establish a sale price if the seller thinks his house is worth 100k over market or a buyer thinks the seller is asking 100k over market because that's what they saw on Zillow.
Further, when zillow gets the estimate of a house wrong it costs them nothing, but there are real costs to Zillow's bad estimates to buyers and sellers.