I'm not sure if you were intentionally referring to the incident where Craig Wright rented a Lamborghini and claimed it was his, but if not that's hilarious... https://twitter.com/DanDarkPill/status/1105082100372393987
Yes. However, then as now, the truth is an absolute defence to a claim of defamation. Had they shown that Liberace was gay, they'd have won the trial.
The issue was that the newspaper in question (the Mirror) never tried to claim that Liberace was actually gay; instead they tried to claim that when they wrote that he was "a deadly, winking, sniggering, snuggling, chromium-plated, scent-impregnated, luminous, quivering, giggling, fruit-flavoured, mincing, ice-covered heap of mother love" that the word "fruit" was not a reference to the then-common slang term for homosexuals, but was just, you know...a word. And that the journalist who wrote it has no idea that the slang term even existed, and in any case whatever was written was just the jounalist's opinion, and shouldn't have been interpreted as a statement of fact, since, obviously, the author didn't really think Liberace was gay.
It wasn't a very good defence, and the jury didn't buy it.
This shouldn't deter him from conclusively proving he is Satoshi. His mere oral claim that he is Satoshi should trigger a massive tax bill anyway. He can't both claim to the world he is Satoshi while telling his tax authority "actually I'm just lying, don't tax me".
I do not know why anyone gives this guy the time of day. There is a way to indisputably prove if he is satoshi and it is the one thing he will not do.
It is like if I start telling everyone the Lamborghini in the parking lot is mine, and they ask me to turn it on, and I spend the next 4 years arguing that it is mine instead of just turning it on.
Although maybe if I do turn it on I trigger a massive tax bill, in which case I should have never said it was mine in the first place.