Based on how things have gone down, I will say that the Jiggle Mallow leak is very, very different from the Grinch Leak and I'll try to condense it to avoid making a wall of text:
-One of the cool things that Sabi did to prove they knew what they were talking about when I first met them last November is that they gave me breadcrumbs to chat logs and conversations among various insiders. Grinch Leak was well known to be fake by a lot of people and a number of insiders tried to steer the public away from it as gingerly as they could. Basically people knew it was fake but couldn't explain it in public without the strong possibility of Nintendo's boot snuggly implanted in their ass.
-Like I said the other day, GameExplain making not one but two videos on it within hours of each other is super suspect. A vast majority of the leaks they bother to cover wind up being real and this is primarily because of their strong connections with Nintendo.
-Behind closed doors, nobody knows if this is real or not while the Grinch Leak was almost an inside joke to insiders in comparison. I can verify that a good number of Sabi's bigger sources are on the fence about it while, for the Grinch Leak, they were able to shoot it down with a single glance based on what they knew.
-It lines up pretty well with how Nintendo will hide things or flat out lie to their employees to keep certain things a secret until the right time. The fact that this leak is a massive blind spot for so many insiders honestly says a lot. I also suspect this may be why Nintendo isn't going on a tear on social media about it, seeing how hilariously bad they fumbled the ESRB leak with Smash 4.
Like we've been saying, it's gotten to that point that someone especially noteworthy would need to shoot it down (not just doubt, full on disconfirmation) or the people behind the hoax would need to step forward and provide evidence that they did it to totally kill it.