What we shoud do is actively try to help [Mami] get stronger, thank you.
That's one of the reasons why my vote included a suggestion for a tandem attack that we could do with Mami where we would make the weapon while she made the ammo. It gives her a vital role in things so that she doesn't feel left out or unimportant. (And if it works out, it could let us make something bigger than Trio Finale that can fire past our 100m range, and fire them faster than Mami can normally make Tiro Finales, which would also be nice to have.) For an individual thing we can do with her, if we can figure out if Mami can make something magnetic, then a railgun or coilgun might be possible for her to make.
Also re:Incubators, they're so advanced that the Heat Death of the universe is the only problem they care about. This means they've solved every other problem.
What I was getting at is that we don't
actually know that for a fact. Even if we assume that Kyubey can't tell falsehoods (and I don't think we know that for certain either), he never actually
says that he's trying to prevent the heat-death of the universe. Madoka asks why he's doing this, and he starts to talk about entropy... but that could be a deliberately-misleading unrelated statement. The conversation takes place in the same episode where Kyubey uses that same method to mislead Kyouko to deliberately get her killed, after all. And Kyubey lays a
lot of bullshit on Madoka in that particular conversation, such as implying that human children are powered by their parents' emotions rather than from food, claiming that he doesn't understand deception (again, in the same episode where he practically gloats to Homura about having tricked Kyouko into killing herself), and trying to justify himself to Madoka by saying that humanity wouldn't want to go to the stars to find that everyone else was already gone even though A) humanity won't take long enough to go to space for entropy to make any difference and B) humanity won't get the chance to go to the stars because
if Kyubey has his way, humanity will be extinct within a week. Put bluntly, anything Kyubey implies in that conversation should be considered extremely doubtful.
I think that Kyubey was doing the same thing he'd been doing the whole series: trying to manipulate Madoka into making a contract. In Episodes 1-3 he tries to get her to contract by convincing her that it will be fun and awesome. Mami's death put an end to that by making her aware of the dangers. In Episodes 5-8 he tries to force her into contracting by making her think that it's the only way to save Sayaka. But Sayaka witching out put an end to that, both because there is no longer a Sayaka to save and by making her realize that contracting to save someone is meaningless because she will eventually become a monster and take more lives than she saves. So now he's trying a new tactic, by trying to convince her that contracting and becoming a witch will help "save the universe". Frankly, I think that's just another one of his cons.
I've been awake for far too long to go into detail about why, if the Incubators are really worried about the heat-death of the universe, they should still want to be Dyson sphere-ing stars to store the energy that would normally be wasted by being radiated out into empty space and sucking up stray interstellar hydrogen to stockpile fusion fuel, even if they do have grief and magic to use as an entropy-free power source. Suffice to say, to be so worried about the (far distant) exhausting of resources that they're willing to wipe out entire species for a new energy source, but
not willing to try stopping the meaningless waste of that resource or build a reserve of it, would be like someone who's so worried about the fact that the world's supply of fossil fuels will eventually run out that they're trying to make more by feeding live hamsters into a pressure chamber to try and compress them into coal, but
not worried enough to stop lighting barrels of oil of fire just for the fun of watching them burn. They're kind of putting all their eggs in one basket. Then again, I've never accused the Incubators of being good at forward thinking, given that they gave the girl whose friends they'd tormented and killed a chance to wish for unlimited power. They're lucky that she didn't wish them extinct or to travel to their homeworld and lay waste to their civilization (which is probably what I would have done in her place). Even as it is, her wish wound up greatly reducing the profitability of the magical girl system for them, so clearly they don't have any way of preventing wishes that work against their interests.
