drop bear
Sr. Grandmaster
This isn't a binary thing. There's a huge range between "super tight" and "loosey goosey". My training is that grip tightens before impact, with both blunt and edged weapons, but never gets "tight as you can", because that causes other muscles to tighten. But that's about technique, and we're talking about what people are likely to do.
The rage thing, I agree on, but I don't think someone's likely to be at that distance with a knife in hand and blind raging. They could be, and I agree it's really likely they're holding tight in that situation. But absent that rage (which I included in my original comment on this), I don't think that super-tight grip he was using is likely. He was focused on trying to protect against a hard kick he knew was coming.
That is a big bunch of nobody really knows one way or another though.