The order is correct. They strip the covers off - this unbinding doesn't destroy them. If they were destroyed at this point "before ingesting" then they couldn't be scanned and digitized. This is just part of the ingesting process. Unbinding improves the quality of the scans, ackshullay. This improves the preservation of the information inside (the digital copy.)

They could totally rebind them after scanning (ingesting is poor word choice, IMO.) They don't. They destroy them or simply discard them.