Twitter is different - there are other big companies that provide as much tech challenges or more (whether they are better/worse than Twitter is another question). Twitter employees have many more options (relatively speaking) than SpaceX employees
Working at Meta/Google doesn't necessarily do that. I'm almost certain most of these companies' moonshot divisions are not as well-run as many startups, nor are these companies assured success in these areas.
Their main products are already at a "don't fix it if it ain't broke" stage, even though many will claim these are broken. I doubt it's exciting work.
Working at Tesla or SpaceX will be like working on a moonshot that's actually taking off. I'm sure it's a thrill. But increasingly, I don't think Musk is level-headed enough to be trusted with such things.
It takes time to reject nitwitted leaders, so we can't expect employees to abandon ship overnight just to prove my point.
The reality is that Twitter as a business (and, imho, as a product) was sorely in need of a course correction. Layoffs, if they need to be done, should be done crisply and thoroughly so that remaining employees don't feel like the other shoe is about to drop.
You rip off the bandaid, it sucks, then you refocus on the work ahead.