The oldest beer in the area HAS to be older than 400 years... But I haven't checked, but beer is old, real old, old everywhere.
Breweries isolate and propagate yeast all the time. Could be a 400yo yeast or a 4mil yo old yeast strain, it's yeast after all. It's old. Just because it was used 400 years ago doesn't matter. It's probably older. It happens all the time, at large breweries and small breweries.
Also Chicha is the wonderful spit based corn beer. The yeast probably won't be missed.
Side note.. I left my orange juice on my counter and it fermented with a yeast strain that's probably millions of years old... Did I resurrect it? Nope. If I plate it and grow a clean culture? Meh it still went down great though.
I don't mean to diss the work of the brewery but everyone does this. The article is just reaching for an article.