Well, they'll be quick to find ways to distinguish Setterfield's theory so they return to the jeers and the catcalls.
I don't know if Setterfield is right. I haven't paid much attention to his theory. But I am amused by the reaction of the atheist materialists. They have a vested interest in their prejudices and will defend them with all the zeal of Holy Crusaders battling the Turks.
So far, the distinguishing feature is that Setterfield's lastest version has light slowing by a factor of 11 million over the last 6000 years, whereas Davies's observation hints at a factor of one part in 100,000 about 12 billion years ago. (Setterfield used to have light going 1060 times faster about 6K years ago, but he apparently decided that was ridiculous.) Anyway, there's about 110 million times difference between what Davies observes and Setterfield predicts.