The problem with Steve's ending is if he were in the original timeline the whole time he didn't rescue Bucky, stop Zola, prevent Tony from being orphaned, etc. which is monstrous and a complete contradiction of everything we've ever seen about him. If he created a new timeline, he hijacked Alt!Steve's life, left the poor chump frozen, and essentially lied to Alt!Peggy everyday of their life together. I'm sure Alt!Peggy wouldn't have been okay with idea that her Steve was an ice cube and the guy who showed up was from a parallel universe. He doesn't come off well in either scenario.