I don't believe that drivel for a second.
If the snow/ice was so hard he couldn't get out with his hands, which are, y'know, solid pieces of body, then I doubt a stream of liquid would have much impact on it either.
Also, urine, being made up of much water, would have frozen (not immediatley, but probablly quickly). Sureley, he used the bottles to hack his way out, but the Sun has to sell papers somehow.