Keep in mind that tapes are still the most efficient storage medium, in terms of both cost and physical space used. What they lack is speed. These characteristics make them the perfect medium for archiving and backup.

To add: there’s no way money can be saved by switching to another medium. Switching to HDDs, SSDs, etc will be many times more expensive, and switching to cloud would be much more expensive over the long run. It’s unclear whether he wants to move existing data to other mediums (very expensive and stupid - the tapes are already there and have almost no upkeep) or just new data (slightly less stupid).