If you read the rest of the reg you quoted you'll see that 1) the reason every OM says adhering is because it's a direct quote of the FAR and 2) under paragraph c and d it clearly states the aircraft critical surfaces must be free of contaminates.

To be completely fair a very dry, cold, snow is about the least harmful of snow. I would very much worry about snow just slightly above freezing point especially if the aircraft just came in from a high altitude flight (cold soaked) and/or morning flight out and the fuel had been cooled to below freezing overnight and now the wings will refreeze the melted snow. I've seen both this winter already myself, and that will bring an airplane down. Quest lost a TBM some years ago due to the latter.

This stuff isn't so cut and dry which is why pretty much every operator prohibits you from departing with anything on the plane.