If the engine has been run at all, the residual oil in the engine will dry out over time making a sticky gunk that freezes things up. This isn’t a bad thing and it certainly won’t remove any life from the engine unless the oil contained in the engine was synthetic oil only. If the engine is new and never run, the factory used a light oil that too will dry out over time. A simple fix for any of this would be to flush the engine with acetone, drain and dry, and re-oil with a good storage oil. I prefer to use Dexron (any variant is fine) automatic transmission fluid (ATF). I use a liberal amount to thoroughly coat the inside of the engine, crankshaft, and bearings. Remove excess and button it back up. This will keep the engine smooth and limber for decades to come.

Just make sure you get all of the acetone out of the engine and the insides are dry before oiling the engine. This ensures the oil gets to where it needs to and stays there. Removing the head and backplate is best as this gets the solvent where it needs to be quicker. Don’t turn the engine through TDC with solvent in it or bone dry as this can scuff the piston. Once it’s oiled and the head is back on it with a glow plug installed, it can be completely turned over a time or two without any issue. I wouldn’t turn a Rossi over cold, but OS engines aren’t very tight, so there is little if any risk of damage by doing so. Some will argue this until they’re blue in the face, but my experience tells me it’s totally fine.

If I may ask - Why have it as a shelf queen?