I usually don't chime in but:
1. Disagree, provided he plans to flee and not
fight. Psychological effect.
Also, a knife is much harder to block due to the size, and will
travel further than anything else in the same weight/size
range. Catching a knife is not feasible due to hand injury,
same goes for blocking too unlike a blunt object. It's also
not easy to dodge a skilled knife thrower (I should know, I'm
one 
)
When I used to teach Jeet Kune Do a few years back I always
advised never to try disarm someone with a knife. It's not
practical. Within 3m, a knife is more dangerous than a gun. Run.
Seriously.
No disagreement here. If you see anybody with a blade
threatening you and you have the option to run... why are you not
taking it instead of getting into a rambo knife fight thrown or
not? Depends on the situation.
A skilled knife thrower isn't exactly the profile of your
average mugger isn't it? If so then GG lor, but the average joe
isn't exactly going to know how to throw a knife in a way that will
end a fight. Unless you can get a deep enough penetration to hit a
vital organ or blood vessel, a fight-ending incap from a thrown
knife is unlikely. A guy closing the distance and stabbing you
repeatedly might.
On the other hand if you are cornered and have no means of
escape and you are reasonably sure the other dude intends on
harming you. Then knowing a disarm or two is extremely useful.
Beats putting your hand up and getting slashed to ribbons.
Additionally, disarms work best if used against a person not
expecting it. Ala. he thinks he has the situation under
control and is using the blade to threaten you from close range. If
the dude is in a fighting stance and expecting trouble,
the success rate of disarms rapidly drop, you're better
off taking a table as a shield or something longer to wack him
with.
There is no right answer, depends on common sense and what fits
the case.
