This wasn't a typical M91/30 rifle, it was an original (although refurbished) WWII PU Sniper made by Tula. People who are very much "in the know" when it comes to these rifles estimate that there are between 5000 and 8000 of these rifles imported to the US. Only a very small percentage of those are Tulas.
Shellac is the original finish on these rifles, not something unique for "storage purposes."
Obviously the rifle really isn't ruined, just the resale/collector value.