That’s the problem with Grogu. Grogu not only isn’t putting his all into his training because he misses Din Djarin, but he would absolutely choose saving Din over saving 100 people in a burning building. That doesn’t make him a bad person, but it does make him a bad Jedi. So Luke makes him choose, Din or being a Jedi. Grogu chooses Din, and he respects his choice.
Grogu’s a baby, though. He’s not able yet to understand complex moral questions or to make life-changing decisions. When Luke puts that choice in front of Grogu, there’s no way Grogu at this point can fully comprehend what that choice means. Naturally, a baby is going to feel a strong bond to their parent, and lack the high ideals necessary to commit to being a Jedi. But that doesn’t mean Grogu wouldn’t have grown into a good Jedi.
Every quote I’ve read says Lucas didn’t pay any attention at all to the EU. He always viewed it as a separate universe from his. Which is why he ignored it in everything he made. The Prequels contradict the EU as does The Clone Wars. You’d have fans yelling at him because he changed Koriban to Moraband and it’s just like, well yeah, he didn’t give a shit. When did he “veto” anything?
Read this. There are some more examples that come to mind. George rejected the idea of bringing Vader back in Dark Empire, for example.