I’m a bit confused by this. We already know that mammoths could have had red hair – I’ve seen specimens of mammoth parts with red hair on them at a traveling exhibit at the American Museum of Natural History several years ago.
I thought pretty much all ancient hair turns to red or blonde anyway as a natural process of aging; pretty sure that was the case with Otzi the ice man, the ice mummies of Peru, various peat bog bodies, Egyptian mummies and so on.
I’m not sure that’s true, or at least, I know it’s not true for specimens up to a few hundred years old – I’ve seen brown specimens that old. It might be the case for hair several thousand years old, but I’ve never heard it. You’d think that the same freezing that retards spoilage of mammoth meat would retard hair color changes, though.
In any event, the article is claiming that the hair could’ve been red or blonde when new, which is somewhat different than it turning red with age.
If it’s true that hair will naturally turn red with great age, regardless of preservation, then my observation of red mammoth hair in the museum doesn’t prove anything.