Ah ok, yeah better to replace the crystal then.
It's not the cosmetic wear that won't make them want to touch it, it's the lack of spare parts. They don't joke around - they'll want to replace things like barrel bridges and barrels complete because of wear. These parts are no longer available new on that caliber. Interestingly, I was looking at that exact same model (but with SS case) on an auction just yesterday. I just didn't feel like adding more to my current pile of vintage swiss projects where I'll be spending months looking for unobtanium parts (the one I looked at had a broken yoke)
Case in point, independent watchmakers would rather repair a worn bridge by staking and/or bushing worn bearing surfaces - techniques like these aren't used by official service centres at all. It's like taking your car to the dealer - they don't want to pull a head to replace a blown head gasket on a modern engine, they'll quote for a new engine. It's an after sales liability issue for them more than anything else.