Of course the snow can be corrected in post, the photo in question was not corrected in post. It’s dark and flat.
You can have white snow without clipping it. I’m a professional photographer and live in Canada (a ton of shooting in snow experience)
As far as hanging clipped highlights and “professionals don’t clip highlights”, you’re wrong there. If the subject is properly exposed (say for example an outdoor portrait) it’s quite fine and accepted to have blown out highlights (for example the sky in the background) As long as the subject (the person) is exposed correctly.
Go watch any weekly Tony & Chelsea Live on Youtube. They’re professional photographers and a constant reoccurring correction on many photos from viewers submitted to the show is to use the Whites and Blacks sliders in Lightroom to add a white point and black point, because so often photos are far too dark and flat. (Exactly like the photo in question in this thread)
Not meaning this as an insult, but perhaps you need to do some more reading on photography or get some more practice before you post nonsense.
*edit to add a video about shooting in bright light/snow*