I get what youre saying. But with Deckard i think that was the point. The replicants act more human and emotive and empathetic than him. The scene where he just coldly and non chalantly destroys Rachel by telling her shes a replicant is a great example of this.
Thats why i prefer to ignore Scott's idea that Deckard is a replicant himself. But then I guess you could say Deckard is so advanced that he even becomes jaded and cynical too!
Blade Runner makes you think. Sometimes maybe it leaves too much up to the viewer and seems kinda threadbare as a narrative. Which again, I can understand that as a criticism.
For decades I've been on Team Replicant. Even before Scott talked about it a lot. To me that was always insinuated. However, I do leave it open and am not saying there is a wrong or right answer.
However I think there is a flip side to Ford being cold compared to everyone else. I do like your theory on it. But I always took it as a few different things:
Memories are implanted in Replicant's and I think most of his "memories" are that of living a cold, detached existence as a Blade Runner. Which just forms his personality of being detached and uncaring. While Rachel has better implanted memories one more similar of a typical childhood and somewhat of a conformable existence. I think that with the new Nexus series (which I believe Deckard to be) their personality is formed differently through their implanted memories.
Being a killer of replicants could very well shape someone like Deckard. Things like the awkward love scene, his violent responses to me show in my eyes that even though he has the implanted memories to pad his emotional response, he still has some hiccups and to me I always felt he was quite new, and not a replicant that has been online for long. Some of his sudden emotional shifts with Rachel to me indicates he is struggling feeling such complex emotions so early on. As are the problems with many Replicants hence the Incept dates and limited longevity.
It will be interesting to see what happened to Rachel, I would assume if she was like most Replicants she would have died after her time was up. Unless Tyrell created her differently, as with Deckard but something else may have happened to her.
I'm also assuming the director's/final cut will be the canon version? At least for the ending since it was always very odd to see such a beautiful world that was unrealistically contrast to what the film had set up the rest of the world to be.