While he was in the elevator with his brothers at The Umbrella Academy, on his way to meet his father, Luther, during dinner, banged on the table and ripped his shirt to show Reginald what he had done to him.
These actions and reactions are not common in Luther, but do fit with something that Five explained in “The Seven Stages.” Five explained to Luther that the closer he was to his older self, the more stages would add to him feeling at The Umbrella Academy.
Luther’s excess rage could be pointing to Luther from another timeline out there, so the Hargreeves will have a lot to fix in season 3 of The Umbrella Academy.
Given all the physical changes Luther went through, the “seven stages” could manifest differently than they did with Five, and the other Luther might not have been as close at The Umbrella Academy.
So he didn’t go through all the stages and the ones he did experience weren’t as intense. A lot of big things happened in season 2 of The Umbrella Academy, and a lot of them are sure to pay off in a future season.
Even if they seem unimportant, like Luther reacting with justifiable anger, but if we detail his personality we can see that he always sought acceptance from Reginald since the beginning of The Umbrella Academy.