PTC put a method in place to prevent problems and you look to work around it; a work around that is as simple as using the operating system to copy and paste. Unlike other software you have used, Creo allows users to make complex systems and encouraging users in bad behavior is counterproductive.
I think you are special in your needs. I see no other users asking for the Save As function to work as you like. That includes the PTCuser board, which goes back before 2000.
What might also interest you is that when you do a Save As, it doesn't switch the context to the new place, but continues to work on the old ones and when you perform a Backup it does switch to the new context.
Thanks for explaining version control software and file naming. It reminds me of when I started in CAD. And, how only 10 years after that when PTC was incorporated and started selling Pro/Engineer. I might still have some of the ads in the old Machine Design magazines from rev 4 or 5 that I kept from when it was first widely marketed.