Anyone that wants to order a reusable RS-25 can have Aerojet Rocketdyne configure and manufacture it that way. See also the AR-22 variant used on the ill-fated DARPA XSP program.
The real issue with that engine isn't its reusability, it's that the industry has learned a lot about rocket engine design, operation, and manufacturing since the RS-25 was developed. That's reflected in the engines available from the likes of Blue Origin and SpaceX. No knock on the RS-25 - it stands as a watershed achievement for humanity in the engineering of thermodynamic systems.
Though calling the SpaceX engines "available" needs the caveat that SpaceX will not make them available outside of SpaceX.
The real issue with that engine isn't its reusability, it's that the industry has learned a lot about rocket engine design, operation, and manufacturing since the RS-25 was developed. That's reflected in the engines available from the likes of Blue Origin and SpaceX. No knock on the RS-25 - it stands as a watershed achievement for humanity in the engineering of thermodynamic systems.
Though calling the SpaceX engines "available" needs the caveat that SpaceX will not make them available outside of SpaceX.