Aesir,
Your confusion is that you somehow think snow and IFR are tied together. They are not, by either regulation or custom, any more that icing and IFR are tied together.
The snow approval is part of the continuing effort to increase operational suitability, a thing all manufacturers do. The use of an engine barrier filter is something the FAA wanted some extra testing to prove its worth, and that is what the Sikorsky team did a few months back (I had dinner with them when they came thru Savannah on their way to the Cold country.) There is not a "hidden agenda" here. I think.