Serious ? No more or less than giving a dentist a bad review, impacting their income and reputation. They will say I am not a bad person to work with and this inaccurate statements have affected my reputation.
A dentist can only sue you for a bad review if the statements are untrue, and harm his reputation. The email doesn't include the name of the bad guy, and even if it did, if the statements are true, then there is no lawsuit to be had. Sure, you could be sued by someone claiming that they're false, but under Anti-SLAPP laws if you prove that it's frivolous you can yourself be awarded $25,000.
Overall it's just very hard in the US to sue someone for telling the truth about how awful you are.
I've read through the transcript of a court case in Australia where the defendant lost 50k for some really borderline comments. Specifically, a vet was "grumpy", and charged 3x markup for some medication, which apparently was true but hand waved away in the hearing with the excuse around delivery and overheads.
The feedback is simply not attributable for outsiders. I don't think there is a legal argument here. And even if the VC was identified, if the writer didn't invent any of those stories (you wanted inaccuracy, right?), there is nothing he is liable for...
Or am I mistaken about US law? I think it is even worse over there, you can basically write what you want, as long as nobody can prove it outright wrong. Just imagine all the New York Post articles somebody would be sued for.
Most outright defamatory articles just end in a "Welp, sorry?"-situation and nothing ever happens, because "It could have been true, right?"