It appears Wright was defamed by McCormack by calling him a fraud and not by declaring that he is not Satoshi. So far as I understand (at least in America), to declare someone to be a thing if he is factually not that thing is to defame the person. If you claim it is your opinion that person is that thing, and did not make a statement of fact, then you are not defaming that person. If McCormack would have said "I believe that Craig Wright is a fraud" or "Craig Wright is a fraud in my opinion" then he may have been found innocent of defamation.

For example, if it was provable that Wright is NOT Satoshi and McCormack said that Wright IS Satoshi then McCormack could also lose a defamation suit against Wright. Because it is impossible to prove a negative, that Wright is NOT Satoshi (regardless if he is or isn't), without having proof to the contrary then he would have chosen a logically impossible defense.

The question the Judge needed to decide is whether Write is in fact a fraud, and since McCormack didn't seek to use facts as a defense, whether Wright was a fraud wasn't presented as a defense as this too is difficult to prove. Even though Wright appears to have defrauded the Judge, the Judge still couldn't decide on that point because the defense hadn't entered this into evidence. Therefore the only option the Judge had was to hold Wright in contempt and to minimally award him for a petty win in a suit where little defense was offered.

I don't see how the court could have made a better decision. Technically McCormack lost the suit but justice was still served. The Judge's professional opinion of Wright's character couldn't have been made more clear.