tl dr: part of the conflict pretext in beyond gets invalidated by simple reasonings related to Spock being part human:
a) IF the vulcans now consider Spock a 'real vulcan (tm)' in spite of his human part, and would therefore accept his kids with a vulcan in spite of them possibly being part human like him, they can't nitpick about his kids with a human either because those would too inherit vulcan from him.
Even if, say, Uhura doesn't want to be a mom now she can be ok about him getting asked to be a donor, which in this 'vulcans don't care about his human side anymore' scenario he should have been from the beginning (assuming he's fertile), just like the other survivors, anyway. Why is this point addressed only 3 years after the vulcan diaspora happened? ¯\_(ツ)_/¯ Any rational person would think that, right after the first movie, ALL the survivors would be asked to donate their sperm and eggs, anyway.
b) IF the vulcans still consider Spock 'tainted' by his human side and not a 'real vulcan (tm)' , they are going to decline his offer to help them regardless he procreates with a vulcan or human or Tilda Swinton. Not to mention that if the vulcans were so exclusive and bigoted still, he'd never find a vulcan lady willing to procreate with him.
However, and in either scenario, the idea that only male/female couples marrying and procreating will save the vulcan race is too outdated and regressive for the reality these people are supposed to live in. And so is the idea that his kids with a human wouldn't be considered real vulcans too (and thus able to continue their legacy, traditions and culture too) only because they are, basically, mixed.
Sure, some might find an interesting parallel between Spock feeling pressure to pick a mate 'in the community', and what happens in our world in some ethnic groups, and the hate and intollerance that interracial or intercultural couples still get. But is it really fitting for trek's ideal of positiveness and inclusinevess to decipt a world that is STILL like that? Especially if done in a way that doesn't even criticize that kind of bigotry, but actually justifies it.
And Spock is NOT T'Pol or Tuvok or Sarek. He's himself the result of an interracial/interspecies couple and that can't be ignored for the sake of drama. Isn't it going backwards with Spock's own struggles as a vulcan/human himself? Not only he'd be forced to erase his human side, but he'd also be forced to pretend his kids are only vulcan. Most of his character development and evolution as someone who can finally embrace both his sides would, essentially, get erased.
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Honestly, it's possible the writers truly only intended that line to be McCoy just making fun of the situation and derailing the actual point (ie Spock wanting to leave starfleet to help his people, thus the issue between him and Uhura really being only related to a long distance relationship and him not wanting to ask her to sacrifice her career for him, and her not wanting him to stay just for her if helping the vulcans was so important to him), but reducing Spock's conflict to this making vulcan babies business is so terribly lame. I get that with this genre of movie we are often asked to suspend our disblelief and we can't even nitpick too much, but if you want to add conflict to the characters you gotta try finding excuses that make sense and don't look like lame pretexts to add drama.
The fact that Spock IS half human should have been addressed in this movie. They (and some fans too) need to stop remembering he's part human only when they want to explain why he's emotional, but then a moment later they pretend he's only vulcan when that does fit their narrative better.
But, again, in my opinion Lin didn't deliver when it comes to the characters and their motivations. From Kirk's conflict, to Spock's and then the villain's motives (not to mention Uhura's side in the break up and her feelings, and Sulu's feelings about his family being in Yorktown when Krall wanted to destroy it).. everything that had any vague chance to add depth is only barely developed, or not developed at all.
I was disappointed by his interviews and the fact he doesn't even seem to really make an effort to talk about certain aspects and explain their story-telling process, adding layers that we maybe couldn't see in the movie, but after thinking about it more maybe it's not that surprising that he seems to have nothing to say about these characters and he didn't seem to be invested in their stories. It's like it's not his story, not his trek, not his characters, not his dynamics. Maybe it's just human and he did his best in the circumstances he was in.
If we get another movie after this, my only real hope is that they find a director who isn't necessarily a fan of tos but they watched these movies and liked them, and genuinely feel like the characters and the story has potential. I want a director who feels like one movie isn't 'enough' to tell these characters' stories and do everything they are inspired to do with this trek.