There is nothing in the article as posted or in the source to indicate that it these remains are of such an age. I'm not even sure if 500,000 years makes any sense for mammoth remains.
Mammoth remains are usually found in recent landslides. Stratigraphy doesn't make sense either, for a a 500,000 year time window. That is too recent.
The article says 1/2 mya.
Not sure I understand your stratigraphy comment. Bottom line is that the time is fine.