I've never heard of this, but it makes enough sense...
  • No reason why it wouldn't work potentially -- and I would venture that like cattle/sheep/etc the material would be de-furred & however processed, so I'd argue the 'too warm' thing would be unlikely.
  • So far as I know, seal was hunted and used by Scots, so why wouldn't seal potentially get used for pipes as well -- people tend to use whats at hand.

I don't know that I'd use seal for a pipe bag, but a seal fur kilt might be nice ... oops, inside out