When the sci-fi adventure series “The Orville” made its debut last year, TV critics opened fire, panning it as “a deep-space dud,” “creatively, morally and ethically bankrupt,” and “the strangest misfire of the fall season.”

Still, “The Orville” survived and thrived. The Fox show about the crew of a spaceship on a mission of exploration and diplomacy had support from a surprising group of allies: “Star Trek” fans, including some who rebelled against “Star Trek: Discovery,” a TV series introduced at the same time.

Jeff...