I am also skeptical of this change.
If true, why would they stop returning parts? They think it costs them money or prestige?
If money, it's costly in time or material. How much time does it take to track and ship a bag of parts? How much are those parts worth? Is Omega really concerned that a few people might put old pushers back in their watch and sell the new replaced pushers to someone, depriving Omega of the price of a couple pushers? Does Omega really think someone is going to swap back an old main spring and reuse it?
Is Omega worried about people buying parts from serviced watches that are old but claimed to be new? People can be cheats in all kinds of ways so I could believe someone would sell a gear as a good reusable part. But come on, how big a market is that and isn't that a problem for the buyer?
I will be more annoyed if I sent them my Speedmaster with a swapped dial and they didn't return my watch. I think they already do this so I would not send them my watch currently anyway.
If this is true, it is strange to consider these discussions and concerns taking place at the company. Seems like they'd have bigger issues.