I know it's not in the movie, only in the script, but I think about this a lot (And if people get to act like Throg is MCU cannon bc I just saw that and it annoyed me, I can indulge in this vibe-based post). It positions Loki as a royal advisor rather than a prince. It's just so weird to have the spare as a royal advisor (with all the risks of fratricide), and it suggests Loki was treated very differently than Thor. A post I re-blogged made me think about this again. And the W4 expect and depend on Loki to talk Thor out of things while also perceiving him as distrustful for that same dependence and proximity to Thor. Not to mention the disbelief everyone seems to have over Loki getting the throne when Thor's away ( Sif was about to attack him but was held back from doing so; got away scot-free; and like that's FAR from the equivalent of "flogged for looking at Loki the wrong way"). He's never publicly announced (which makes his claim shakier and opens him up to suspicion), and that Frigga acts like Loki will just hand over the throne to Thor when he comes back.