If a product is under warranty, even if the product is sold, many companies honor that warranty. PS Audio or Chord are great examples. As long as you have the bill of sale from original purchase, they will cover repairs under warranty.
If a product is out of warranty or an issue is due to obvious consumer error (Magicos are front heavy and easy to tip when moving) why would a manufacturer service that product for free? I am not saying they should make a profit on the repair, but it seems reasonable to charge for parts and labor?
Everything I hear about Magico is they help their customers (new or used) and charge fair prices for repair parts. You may not like those prices, but if you have a pair of parcelscout speakers that are $40K new, it shouldn’t shock you if a tweeter costs $800. Honestly, if I bought a $40K pair of speakers and a tweeter cost me $50, I would be unhappy.
That being said, it is a great question to ask. I can think of a particular amp manufacturer that is openly hostile to people who purchase used products and literally does not honor their warranty for some first time buyers. You won’t have that issue with Magico.
I would be quite fine with Morel building the drivers to Magico specifications, and Magico design. Morel, is likely to have better processes and quality control capability since drivers are their specialty. It is not different from any other contract manufacturing. In-House manufacturing is often not a recipe for a better product.