A submarine-launched drone is primarily a reconnaissance tool

In what scenarios would a submarine-launched UCAV be useful?

Its clearest uses are reconnaissance, surveillance, and targeting, although the specific design needs closer study.

Reconnaissance is the clearest role for a submarine-launched uncrewed aircraft. Surveillance and targeting information can extend a submerged boat's awareness beyond its own sensor horizon. The named design would need further study before its specific capabilities could be assessed. A plausible mission does not by itself establish that one particular vehicle can perform it.