well this is America, you can sue anybody for anything with any reason. But
bear in mind that it's not free to do that. You can sue, sure, but one can
counter sue too. If you lose, you will be accountable for legal fee. This
business is on the losing side because the reviewer didn't say anything that
isn't true and there is the second amendment right of free speech. If they
really sue the reviewer, chances are the reviewer is going to counter sue
for emotional distress. Guess who is more likely to get money out of it?