I can understand that they want to err on the side of "too much humanism" instead of "not enough humanism", given where Star Trek is coming from.
Arguments of the form "This person might look and act like a human, but it has no soul, so we must treat it like a thing and not a human" have a long tradition in history and have never led to something good. So it makes sense that if your ethical problems are really more about discriminated humans and not about actual AI, you would side more with rejecting those arguments.
(Some ST rambling follows)
I've always seen ST's ideological roots as mostly leftist-liberal, whereas the drivers of the current AI tech are coming from the rightist/libertarian side. It's interesting how the general focus of arguments and usage scenarios are following this.
But even Star Trek wasn't so clear about this. I think the topic was a bit like time travel, in that it was independently "reinvented" by different screenwriters at different times, so we end up with several takes on it, that you could sort into a "thing being" spectrum:
- At the very low end is the ship's computer. It can understand and communicate in human language (and ostensibly uses biological neurons as part of its compute) but it's basically never seen as sentient and doesn't even have enough autonomy to fly the ship. It's very clearly a "thing".
- At the high end are characters like Data or Voyager's doctor that are full-fledged characters with personality, memories, relationships, goals and dreams, etc. They're pretty obviously portrayed as sentient.
- (Then somewhere far off on the scale are the Borg or the machine civilization from the first movie: Questions about rights and human judgment on sentience become a bit silly when they clearly went and became their own species)
- Somewhere between Data and the Computer is the Holodeck, which I think is interesting because it occupies multiple places on that scale. Most of the time, holo characters are just treated like disposable props, but once in a while, someone chooses to keep a character running over a longer timeframe or something else causes them to become "alive". ST is quite unclear how they deal with ethics in those situations.
I think there was a Voyager episode where Janeway spends a longer period with a Galileo Galilei character and progressively changes his programming to make him more to her liking. At some point she realizes this as "problematic behavior" and stops the whole interaction. But I think it was left open if she was infringing on the Galileo character's human rights or if she was drifting into some kind of AI boyfriend addiction.