According to the article they really did prefer modern instruments.

>The results revealed the two most-preferred instruments to be modern, while in third place was a violin from Stradivari’s ‘golden period’. At the opposite end of the scale a Stradivari drew the poorest result and a modern instrument was placed second-last.

But they couldn't distinguish which instruments were which reliably. Suggesting that even if there is a preference, it's very weak and probably doesn't matter very much.