Truth is already a defense. This case establishes a new defense; it doesn't invalidate the exsisting ones:

Justification

The statement was true

Privilege

If you have some legal or moral obligation to disclose the defamatory material - for instance, you are providing a reference for someone looking for a job, or you are testifying in court.

Fair comment

You are allowed to criticize as long as it is done fairly and is based on fact.

That's not the meaning of this ruling at all. Because this is a defence, you would have the burden of proof. It's your job to show that you did try to contact them and they refused comment. Furthermore, the tests effectively establish that you must have enough information to justify the possibly-defamatory claim as much as is reasonable given the urgency of the issue. You have to prove that you did everything reasonable to determine if then rumour was true or false and then (and only then) went forward with publishing a report of an unsubstantiated allegation.

In theory, you could concoct a large amount of fake evidence to prove this to the courts, but a) it's not easy b) you'd have to convince them that the other plain was lying when he says you didn't contact him c) it's highly illegal (in Canada, the maximum prison term for perjury is fourteen years) d) the same would be possible without this new defence.

Ugh... I wish people would stop mixing up the difference between trademark and copyright. Notwithstanding that the Vatican is a sovereign state and can do whatever the heck it wants within its boundaries, what they're really declaring is that the trademark of the Pope is going to be reserved for their exclusive use. Copyright isn't even involved here.

Your point is well made, but the UltraHLE threats occurred before the court decision that an emulator is legal. Nowadays, Nintendo's legal department is very careful to sidestep the issue of whether or not the emulator program or a data backup made from a physical medium (as opposed to another copy of the same game downloaded over the Internet) is itself legal, instead focusing on the fact that downloading ROM images of games over the Internet is illegal.

How much would you pay for the computer Linus used?

I rest my case.

It's worth pointing out that Nintendo merely wants to find out if infringement occurred - they're almost certainly as aware as every other game company that emulation is legal. It's quite possible, however, that there was indeed some copyright infringement, such as in acquiring the game, and they want to be sure that their competitors are playing by the book.
This is reasonable, in my opinion.

There's Private Browsing for a reason. Ctrl-Shift-P to the rescue!

The issue is one of anonymity. Someone could (comparatively) easily phreak a machine when a specific person walks into the polling booth so that they could determine that person's vote. The integrity of the results is not compromised, however; there is no threat of vote-stuffing or fraud.

A system language with run-time reflection is one of the worst ideas I've heard this year.

And I've heard a pitch for a language where the compiler can be changed by a running program... retroactively.

It says you have the license to run it, which would, I suppose, include copying it into RAM since that's how computer programs are usually designed to be run.