Sure, it could be a universal binary, or something interpreted, or bytecode using an existing VM. But the shim would be something small, and could probably be

Sure, it could be a universal binary, or something interpreted, or bytecode using an existing VM. But the shim would be something small, and could probably be reused as a standard installer for many programs. My argument wouldn't be that a universal binary is never the right approach, but that it seems wasteful to make every binary support multiple architectures instead of using a more targeted approach.