Ben Kenobi’s strained relationship with Own and Beru Lars will be explained by the villainous Imperials they both face in Star Wars film in 1977. These encounters, combined with the respective missions of Kenobi and the Lars family, will explain why Owen wants Kenobi to stay far away from Luke Skywalker in A New Hope.
Obi-Wan Kenobi worked alongside Yoda and Bail Organa in Revenge of the Sith to set in motion the ultimate defeat of the Galactic Empire and the Sith. While Kenobi watched over Luke Skywalker, waiting for the right moment to begin training him as a Jedi Knight, Owen and Beru Lars raised him as a moisture farmer, giving him the closest thing he could have to a normal life, even if it’s on the harsh and hazardous world of Tatooine.
Obi-Wan Kenobi’s trailers show numerous Imperial villains, including dark side-wielding Imperial Inquisitors and Darth Vader himself. Owen Lars is even shown facing off against an Inquisitor in one moment. Owen and Beru want to keep Luke Skywalker safe more than anything, and their fears for his life were embodied by the Imperial Inquisitors. Owen and Beru know that Kenobi, despite his benevolent intentions, brings Luke closer to that same danger, so it’s understandable why Owen does everything possible to keep the two away from each other.
In A New Hope, Owen lies to Luke, telling him that Obi-Wan Kenobi died around the same time as his father, Anakin Skywalker, as well as trying to downplay Ben's potential importance by dismissing him as an eccentric hermit. While Owen and Beru are preventing Luke from leaving Tatooine and ing the Rebellion as he wished to do, they’re doing so in the hope of protecting him. The two love Luke like a son and are all too aware of what the life of a Jedi did to his father.
Owen and Beru are unique as Star Wars characters in that they’re completely ordinary beings who don’t take part in the franchise’s grandiose wars, therefore giving them a distinctively grounded perspective of the universe. This also worked to Luke’s advantage, as his relatively normal upbringing on Tatooine meant that he never lost sight of the ordinary beings he’d eventually protect as a Jedi Master. While Imperial Inquisitors are dangerous for trained Jedi Knights, they’re probably far more terrifying to people like Owen and Beru, who aren’t accustomed to seeing their deadly lightsabers and supernatural powers.
While Owen must survive his encounter with an Inquisitor (the Third Sister), he and Beru will tragically die in a later encounter with Imperial forces. Despite their best efforts to keep away from the galaxy’s conflicts, their seemingly-harmless new droids led Imperial Stormtroopers to their farm, where they were brutally killed, a fate that Luke would have shared if he hadn’t left the farm to search for R2-D2. Owen’s encounter with a villainous Inquisitor in Obi-Wan Kenobi perfectly explains why he’s so adamant about keeping Luke away from Ben Kenobi, and his tragic fate in Star Wars horrifically demonstrates the danger he’d been protecting Luke from as well.
