Damages to LED from accumulated snow?
The LED group needs to be waterproof anyways, and it needs to withstand dirt that's thrown at it from the tire at quite some speed. Snow won't penetrate any further than water. Also, since the fender looks very plastic to me, it won't be attacked by the salt that your city may have used to clear the roads.
As such, I believe that your LED should be perfectly safe and won't be killed by any amount of snow that you choose to bike through.

Cables may be a different matter as blocks of snow can tear at them in ways that water can't. But as long as the cable to your rear light runs straight up in the middle of the fender, that shouldn't be an issue.