Not sure where that info came from, it wasn't well researched in other areas (that the only two chicken breeds that lay blue eggs, when there are several others) that they called araucana the same as "Americana" (their spelling not mine). With the easy well known and documented mistakes in the article it does not inspire confidence in me that they actually know what they are talking about in the more technical areas.
That being said a retrovirus ages ago effecting dna changes that then were passed on the good old fashioned way is plausible at least on the surface. However the article title makes it seem as though the chickens now laying blue eggs have a current ongoing virus, very inflammatory and misleading considering the content of the article. The article also seems to hint at the possibility this is an unhealthy virus, which according to thousands of years of blue egg laying chickens in home flocks and the wild around the world seems a clear indication that if it was started by a retrovirus ages ago that it has not been harmful to these chickens, again not inspiring confidence in the content of the article and seemingly needless inflammatory statements.
Sorry I forgot to quote, this was about the blue egg virus article