Exactly!!!!
Nobody I know of has ever brought KHV home by exhibiting koi in a show. Four ways I've heard of to get KHV.....
One, from an internet koi purchase.
Two, from a fish given by a friend (koi or goldfish).
Three, from a koi purchased at a show.
Four, from a koi purchased at a dealer or breeder.
I'm certain there are other means of getting this disease in your fish, but those four seem to be the ways I've heard most often.
Of course, even in all four of those ways, proper quarantine procedures could have prevented the infection.
Now, as to the spread of other diseases...I've seen costia spread through a show on more than one occasion, even when everybody was very careful. Tells me costia is easier to spread than KHV.
And I very much agree with shooting anybody knowingly bringing infected or KHV survivors to a koi show.
Off to go electrofishing...
Brett