I think there’s an argument either way - Luke is warned by Obi-wan to bury his feelings deep, lest they be used by the Emperor, and they are indeed used that way. Luke tossing away his sword could be read as a rejection of his attachment to his friends, and this reading would vindicate Obi-wan’s warning.
However, I think it’s important to note Luke’s words in this moment. He doesn’t say anything about giving up his friends, accepting their deaths, or acting as an emotionless island of calm; no, his words are ‘I am a Jedi…like my father before me.’ He is standing over the body of his father, still believing in the ultimate goodness of the man despite all of Vader’s actions to the contrary.
I would argue that while Vader and the Emperor have been threatening Luke’s friends in general and Leia in particular in order to goad Luke into attacking, the true test has always been whether Luke loses faith in his father. This is because Luke’s entire journey to becoming a Jedi was predicated on the myth of his father, the heroic Jedi Knight. If this myth can be shattered, if Luke comes to believe that even the greatest Jedi can be corrupted, then Luke himself must fall.
And so when Luke declares ‘I am a Jedi…like my father before me’, he is affirming that some core of Anakin Skywalker was never corrupted by the Emperor, and thus Luke is impervious to the Emperor’s tricks as well. Luke is choosing to place his faith in his father, declaring a connection in that moment between father and son that none of his mentors believed could still exist.
This reading, I think, even adds depth to the precept of ‘no attachments’ in the prequels. One interpretation of events is that Anakin’s selfish love turned him to evil, and that Anakin should have listened to his mentors and abandoned Padme to her fate. But in another reading, it was the Jedi’s teaching of non-attachment that caused them to become isolated and vulnerable, and that led Anakin to reject the Jedi when their teaching conflicted with his love. In this reading, Yoda’s teaching was in the wrong, and when Yoda repeats his mistake with Luke, it is only Luke’s independence and relative lack of training that saves him from the pitfall that doomed his father.
In the end, I think the question to ask is, what is more likely: that Luke, whose primary character trait throughout the OT is that he will do anything to save his friends, is suddenly able to emotionally distance himself from those friends enough to defy the Emperor? Or is it more likely that Luke, who has been proclaiming the goodness of his father the entire film, is able to persevere in that faith until the end? I think that the latter interpretation is more valid, and I think if you asked a random viewer in 1983, you would probably hear the same.
The question here is, to me, what is Luke’s character arc about and how does his situation play out? Luke doesn’t have to say what he’s doing in the scene to do it. As what he’s doing is still refusing to allow those he cares about to be used to get him to compromise.
I think Luke can choose to not see his dad as a total monster, see his humanity, and also choose to resist the pull of his emotions being used against him. Luke refers to being a Jedi in that moment, and resisting those things is what Jedi are supposed to try to do. That is what Luke does in that scene, refuse Vader and Palpatine threatening his loved ones to control him. That’s, at least, part of what drives him in these scenes to me.
This is overcomplicating it and it seems contradictory only because the attachment thing was made up in 2002 to create a “forbidden love” angle for Anakin, like I’ve been saying.
What’s contradictory? What Yoda and Obi seem to speak on in TESB and in ROTJ seem moreso consistent with that idea, than not, to me.
What does it change? Yoda didn’t exist until TESB was developed. It doesn’t change that the story has him there.