Yes. Niemann has admitted to cheating in the past, and has apparently been banned from some past events for cheating. So Carlsen can safely relate to the public that he believes Niemann to be a "cheater". But to say for a fact that Niemann cheated in a specific match, he'd be communicating a statement of fact. If that statement is false, or could colorably be argued as false, then Niemann can take him to court for defamation, and even if Carlsen prevailed, it would still be painful and expensive.

Remember that statements of opinions, including opinions that are analyses of previously disclosed facts, are protected from defamation claims. Defamation can only consist of a damaging false statement of fact, or the allegation that you're aware of specific undisclosed facts like that to support your opinion.

Note that the above defamation is the US-based one, I believe.

Other countries have vastly different statues, and in some cases true statements of fact can be defamation (if they were not widely known, I believe).

I think the UK is that way.

You could call out Lord St. Buggering-Little-Boys, complete with films, DNA evidence, and witness testimony, and still lose (and be on the hook for legal fees).

Japan is like that - making someone look bad by publicizing their provably-true behavior is considered defamation

But he already accused Neimann of cheating ... the slander is already there.

If I were Neimann I would actually sue now.

That's why Carlsen is being very careful at what he does.

He hasn't said anything beyond provable facts, and let people read into his actions what they want.

Suing someone for defamation because they resigned to you in a tournament is going to be a pretty high bar.

Neimann has already admitted to cheating in the past, so that claim is dead.

You're allowed to make "very strong implications". The other word for that is "opinion". You're in trouble if you say "I've been given secret information that shows Neimann cheated at the Cup", but if all you're saying is "based on these factors, which by implication you yourself could evaluate, I believe he's cheating", you're offering an opinion based on disclosed facts, and that defamation claim won't survive dismissal.

(I'm not a lawyer, I just nerd out on this stuff, happy to be corrected).

In a carefully worded statement like this (clearly it has been reviewed by legal council) you will say things that cannot be charged as defamation in the appropriate courts.

It's also a gambit to get Hans to say something like "sure, Carlsen, say whatever you want" which could be used as a defense in a defamation case.

There's even a hint that Carlsen has evidence of cheating that has yet to be revealed (but not this game).

I was about to say that the word is counsel but, come to think of it, Carlsen can well afford an entire council of lawyers.

Ha! Good catch (did you have a computer help you!!!) but I daresay Carlsen's lawyer and perhaps Chess.com's have reviewed the statement.

The aforementioned Twitter Gambit first having been developed by Capablanca.

Cheaters gonna cheat. Personally I don't think Carlsen needs to elaborate any further.

If you're 49% sure someone cheated against you / would cheat against you, that's probably enough to make you never want to play against them, but also not enough to prevail in a court case.

Read his statement again. He does accuse Niemann of cheating against him at the Sinquefield Cup. His reasoning is more feel/behaviour based.

Please don't post manufactured troll quotes.