He didn't really explain the full problem so maybe I am not fully appreciating the situation here, but this seems like a pretty big overreaction for a stupid request from some a single user.
If I add one of the latest in the series of my own experiences. Once upon a time someone wanted to scam me on a website deal. We figured out who it was (it was easy, he was the owner of the domain, paid for the hosting etc.) and published the details (we were not the first, he's quite a known scammer around here, we found numerous blogposts about him). He was even featured in a local newspaper. Fast forward 5 or so years and I get a Cease and Desist letter from him (or something looking like that) that the information in my blog post is not accurate and he will sue me. I quickly see that google doesen't bring much about him nowadays, in part to people not caring for their blogs/doing redesigns and in part of him sending out "scary" letters. Of course I could fight it, I had a lot of concrete (I was told court grade by some lawyer acquaintances) proofs. But was it worth my time? My effort? My psych? No. I redacted the blog post and let it be. I don't feel good about it, because that means he will try to scam people that could'we been warned from my post. But I wagered it and left it all behind.
EDIT: grammar n'stuff
And, the better your case, the more soul-draining it is. I would imagine that it is easy to comply when one knows he is in the wrong. But, when one feels strongly about the cause and is advised that he has an excellent case, then capitulation feels like being bullied and extorted into compromising one's principles. This, even when it is frequently the most prudent thing to do.
So, one is left with the sad choice of either compromising his principles or fighting indefinitely at significant cost in time, money, and emotional energy.
Once you proceed past the "first sign of conflict", you will quickly sink a lot of cash. You don't get a refund if you later decide to stop, nor any other credit. That money is gone and either you keep going until you a.) win (or lose) a protracted, costly battle; b.) bankrupt your cash, energy, or will; or c.) find an opportunity to settle and stop the bleeding. By then, the damage is done.
So, if you decide to proceed, then you are signing up for significant cost and a ride for which you have limited control. They will keep throwing stuff at you to entangle and frustrate you. If you take the suit as far as discovery, then you can get into the high 6-figure or even 7-figure range before you know it.
And, before you get to discovery, the motions, counter-motions, and other pleadings can easily get you to six figures within a few short months or less (depending on the complexity of the case).
If you are a small business, it can be a non-starter, especially when the plaintiff is a much larger (and hostile) company. I've been through it personally and I decided not to "capitulate at the first sign of conflict". I was pissed, they were wrong, I wouldn't be bullied, etc. So, I fought it.
We handily beat them back on the initial injunction they were seeking. Based on the merit, we knew we'd win that easily. Still, it cost me ~$20K to actually do it. It doesn't matter how weak their case is. They can make you bleed to prove it. The standard for having the suit labeled frivolous is extraordinarily high and you almost assuredly will not recover your legal fees.
We kept fighting, using some of the foundation (research, etc.) laid during the injunction battle to reduce costs. Still, by the time, we reached the mandatory (in the state of CA) settlement conference (where we decided to settle), we were out over $100K. So, that was the price of "not capitulating at the first sign of conflict". Of course, we didn't have to concede everything they initially demanded, but that small victory felt a bit Pyrrhic.
And, none of this cost includes the time, mental energy, and stress involved. If you are running a small business, you likely don't have time/energy for it. So, beyond literally bankrupting you, it can damage your business (perhaps irreparably) in other ways.
Source: I've run a public forum with anonymous posting for about 10 years and get regular legal/removal threats. Had four in one day the other week. None have ever proceeded beyond a threatening letter from a lawyer and most don't get past "I've printed this out and I'm taking it to my lawyer."
In the past I've given lots of information about requests to moderate or otherwise remove content from forums I run.
Then I was hit with a cease and desist, and again provided transparency of it. The very predictable Streisand effect kicked in, and then I was hit with a harassment case too (for disclosing the details even though I knew it would likely trigger Streisand).
It was all resolved quite peacefully, but one fire-fights these things reasonably over the years and get to learn that the other party is usually not being reasonable. You can either result in escalation, or you can calm things down.
It's a lot easier to pick the option that calms things down if it's available to you. And in case above, that was apocalyptic, to close the list without disclosing detail behind it.
The last straw really breaks the camels' back. Once broken, it's not getting up to fight on. Life is too short.
Receiving legal threats (either real of vague promises of one), being accused of censorship and denying someone's right to freedom of speech (and having to explain that's not how free speech works), cleaning up spam and trying to sort out fights between users really wears you down after a while.
A lot of work goes on behind the scenes of running a 'community' and it can be stressful, draining and generally not fun.
You are free to try to step in to the gap created by the closure of this list and run a replacement service. I'm sure someone will.