You don't need to do anything. After some thought, I decided you had already reset the drive to a non-member drive, and the restore is simply putting the AHCI drivers back into the system. In this computer, RAID On basically enables the RAID configuration, it doesn't make a RAID, but the important thing is that the AHCI drivers are required. Since that is the way the computer was originally configured, you had to enable the AHCI so the computer would boot. Don't worry about the RAID, especially since you don't see the degraded RAID message.
Thank Goodness! Good work, and don't forget to clean up the second drive before using it!