It's why as an audio nerd I was so fond of blind tests (as are a number of UK magazines). Sometimes, what we think we know isn't what we in fact know.
The points about concert hall projection are certainly valid. A point could also be raised that more experienced violinists know how to extract the maximum from an instrument, in the way that a great guitarist can make an instrument do things that a less-skilled player can't.
But these violinists were performing in an international competition (most likely the International Violin Competition of Indianapolis), so it isn't as if they were sucky players.
As usual, both sides will take from it what they need, and agree to disagree. But stories like this are always fascinating for what they say about expectations. And the parallels to the audio hobby are abundant.