It's a major pet peeve of mine when people's conspiracy theories don't even make sense even if you accept the theory at face value:
1. If you want to fire people for performance or other reasons, it's true that a great time to do it is during layoffs - there doesn't need to be any rationale given, and there is nothing to sue over when a hundred other people are also being let go for non-performance reasons. So if you're already having layoffs, why again are you hoping for some people to resign??
2. Why on Earth does your friend think having multiple rounds of layoffs will convince poor performers to resign? That doesn't make any sense. If anything, it's usually the crappiest people who are OK stocking around when a company becomes paralyzed during layoffs season - it's top performers who see the writing on the wall and go elsewhere.