I get why people think this is “dirty”, I just don’t have a huge problem with it. If he gave him a concussion by hitting him in the ear hole with his helmet I’d say dirty. This seems more like a fun little shot, nbd. It’s football, you are looking for contact, having an angle is advantageous.
As far as the “injury” goes, being cold and getting knocked over had more to do with it than the play being particularly dirty did.