Hook has a jekyll and hyde persona, call that an effect of 300 years in Neverland. In this scene he’s Killian and he’s only ever been Killian to Emma in the past 300 years.
This is the Killian that was in Tallahasee and Emma’s the only person that’s ever brought that out of him. It’s because of this understanding with one another that he can be himself with her and only her.
I totally understand this. I do. But I don’t think you can ever devoid someone of a persona they’ve been carrying for 300 years. Hook doesn’t just go away, he is always going to be both. Just like Regina will always have some part of the EQ in her, even when all she wants is love. Rumple will always struggle with wanting power after having it for so long.