Why a tender's protection depended on staying put

How would a seaplane tender protect itself if it had to move?

Its best protection came from a defended fixed anchorage; routine movement would require escorts and undermine the concept.

A tender staying in one place could deploy its own defenses around the operating site. Its relatively low value would also make it a less attractive target for a major enemy force. A tender moving at sea would need protection supplied by other ships. This favors employment in secondary theaters, while fleet carriers provide aviation that can keep operating as the fleet moves.